The Sinking of I-70

The I-70 in port during May 1941 after a collision with the submarine I-69 during exercises. The submarine was repaired and sent to support the Japanese attack on Pearl Harbor.

Portrait of Lt. Clarence Earle Dickinson, Jr., VS-6

At 0553 that morning Enterprise and its task force, after having passed between Oahu and Molokai on the 9th, was continuing its search toward the north and northeast along the sea lane toward the mainland’s west coast, and launched her first group of planes to fly the morning search patterns. They were looking for Japanese surface ships, aircraft or submarines. It was to be a day of frequent contacts with enemy submarines, intense flight operations, sightings of submarine periscopes as well as submarines running on the surface, enemy torpedo wakes sighted tracking toward Enterprise, aggressive depth charge attacks by Enterprise’s submarine screening destroyers, a zigzagging task force, sharp changes in speed from flank speed to engines stop, and abrupt changes in direction at flank speed with the great ship heeled over twenty to thirty degrees opposite the direction of turn. The day began with a bang.

The last aircraft among the first group to launch lifted off at 0602. They were from Bombing Squadron Six, and within seventeen minutes of the first launch, one aircraft from

VB-6 sighted an enemy submarine running on the surface. At 0618 Enterprise began launching a second group, and completed the launch three minutes later. While the second launch was in progress at 0619, SBD 6-B-17, from VB-6 reported a submarine at latitude 22 degrees 30 minutes north, longitude 156 degrees 30 minutes west, course 080 degrees true – a course nearly due east. At 0630 hours, the plane’s crew reported they bombed the submarine.

The pilot, Lieutenant (jg) Edward L. Anderson, with Radioman/gunner Third Class S.J. Mason in the rear cockpit, was searching an area forty miles south of Enterprise at 300 feet altitude. In his action report of 15 December, he wrote,

…sighted a wake made by [an] enemy submarine. The vessel was close and [the] conning tower [was] sighted above water. The submarine was making a crash dive. I pulled up to 800 feet over the enemy and released a 1000 pound bomb which was seen to explode approximately 50 feet aft and somewhat to port of the submerging submarine’s conning tower. Oil appeared on water. No further evidence of submarine.


The last aircraft airborne in the morning launch was at 0621. At 0627 hours, Ensign Clifford R. Walters, flying SBD 6-B-2 from Bombing Six, reported sighting a Japanese submarine bearing 020 degrees from point option, the point from which the squadron dispersed to begin flying search patterns. He had reached the end of the search mission’s first navigation leg, and after rendering a report and being informed that ten surface vessels he had spotted were Task Force 1, detached from Task Force 8 to meet Saratoga and escort her to Pearl Harbor, he turned toward the Enterprise. In his 13 December action report he recounted what occurred:

…While en route back to the ship, I saw a submarine on the surface. Tracking the submarine in the sun, I was able to see it was large, no flag, and traveling at about 16 knots. I decided to bomb it in a glide bomb but the higher winds pushed me into a dive bomb attack and with little flaps. I dropped the bomb at 1800 feet and was unable to pull out until about 600 feet because I was traveling at a speed of about 240 knots. The submarine submerged just before I was in firing range with the .50-caliber fixed guns. He submerged slowly and blew many bubbles on descent. The 1000 pound bomb landed about 40 feet on the starboard quarter. I believe shrapnel hit the submarine as the bomb had an instantaneous fuze. My Radioman, IVANTIC, J.J., RM3c, strafed the submarine with his .30-caliber free machine gun as we pulled out of the dive. I remained over the spot for a few minutes and the submarine did not surface again, so I returned to the ship. I saw no oil on the surface.

Ensign Walters’ action report suggests he probably had attacked and damaged the I-70. His Imperial Majesty’s submarines I-25 and I-70, were two of the Japanese combatant’s attacked by Enterprise aircraft that morning. I-25 reported being attacked with a depth charge by a TBD-1 “Devastator” of VT-6, but dove to 130 feet, and the depth charge exploded above her, causing no damage. After waiting thirty minutes, I-25 returned to periscope depth and was attacked a second time, and again dove to 130 feet, causing the depth charge to explode above her, with no damage.

The I-70 was less fortunate. She had been damaged by a bomb released by an SBD in the early morning attack, damage that forced Commander Sano’s decision to surface, and continue running on the surface. Considerably smaller and carrying less firepower than the Type C.1 cruiser subs that carried the midgets launched into Pearl Harbor, the Type 6A submarine built in 1934 was 336 feet long, 27 feet abeam, with a hull depth of 15 feet; displaced 1,400 tons normal, 1,785 full, and 2,440 tons maximum submerged; carried a 4-inch instead of a 5.5-inch gun; six instead of eight torpedo tubes; and 14 instead of 20 torpedoes.

The end came in the early afternoon 121 miles northeast of Cape Halava, Molokai, Hawaiian Islands, at latitude 23 degrees, forty-five minutes north, longitude 155 degrees, thirty-five minutes west. Lieutenant Clarence E. Dickinson, the pilot who had, himself, been shot down by swarming Japanese fighters over Oahu the morning of 7 December – costing the life of his radioman/gunner – had his opportunity for payback, and succeeded. He struck with one dive bomb pass, and the submarine sank, leaving four sailors in the water who later perished.

Lieutenant Dickinson, writing in his 1942 book, The Flying Guns, had no way of knowing the identity of the submarine he and his Radioman/gunner sunk that day, but vividly recalled the sequence of events leading to I-70’s destruction.

…the morning scouting flight picked up three or four submarines on the surface. Three or four seen in the area covered by the scouting flight logically meant that there were an awful lot of Jap submarines around. So, about 11:30 in the morning of December 10, Admiral Halsey decided to send three planes to each place where a submarine had been sighted. I was detailed to make this flight.

At that time no one had been assigned to me in place of Miller, [my radioman-gunner killed over Oahu the morning of 7 December.] So I took a lad named [Thomas E.] Merritt, about twenty-one; very nice looking. This young man turned out to be an extremely reliable radioman and gunner, one of the best in the squadron. But this was going to be his first chance for revenge.

The submarine I was to hunt for was supposed to be about 125 miles north of Pearl Harbor. However, when I had flown about 75 miles south I wasn’t expecting to find the submarine waiting for me; that was only my starting point, really. It had been seen at six o’clock approximately where I was by a half hour past noon. Where could it have gone in the Pacific Ocean in six and a half hours? I decided the best thing to do was to fly a rectangular course around the position where the sub had been last sighted and give emphasis to the north and east. I went twenty miles south, then traveled thirty miles on a leg to the east, then began the leg forty miles north. I had left the carrier at noon. It was now about half past one. Nothing but sky and water anywhere in sight.

The wind was blowing pretty much of a gale. There were white-capped waves, but visibility was excellent. I could see twenty-five miles in any direction, possibly thirty miles. Just as I reached the north corner of my rectangle, lo and behold! Way over to the northeast about fifteen or eighteen miles away there was a great big submarine running on the surface. It was pushing to the northeast just as fast as it could go. It was obviously a submarine but it looked to me to be the biggest I had ever seen. I talked to the carrier immediately.

“This is Sail Four…Have sighted submarine. Am attacking.”

The carrier acknowledged my message. I was already heading toward the sub. I was about 800 feet off the water then and to make a good dive bombing attack I would have to climb up to 5,000 or 6,000 feet at least. So I started climbing. I suppose I was climbing while I was talking with the ship. Now, to go straight ahead fifteen to eighteen miles in a scout bomber is one thing, but it is something else to go a mile up while you are going eighteen miles ahead; moreover I was flying right into a heavy wind. It would probably take six or eight minutes for me to get into position to do my job. I had certain chores to do in connection with my craft of bombing. I had to “arm” the bomb mechanically before I dropped it. I had to do certain things to it that would make it explode on contact. Threaded through the fuse of that 500-pound bomb I was carrying were what we call “arming wires.” These arming wires have to be pulled out of the fuse before the bomb is dropped, else it will fall as a dud. When the wires are pulled out, two parts of the fuse move into position, the “vanes” on the fuse rotate properly and on contact the bomb explodes. Consequently the height of futility in bombing is to neglect to arm your bomb. The arming of the bomb is the pilot’s job, but to make sure that none of us forgets in the excitement of the attack, it has been made a part of the gunner’s duty to check with the pilot just as your partner checks you against a possible renege in a bridge game when you fail to follow suit by asking politely, “No spades?”

I had plenty on my mind climbing to a good diving position. I didn’t see how I could stand the disappointment were the Jap to submerge. Next thing I knew he was shooting at me; just as soon as I was within gun’s distance of him the sub had opened up with two deck guns, four or five inchers. The Japs manning those guns were not especially good shots but, after all, this was the second time within three days that I had been shot at and I was a little tired of being on the receiving end. I was getting sensitive, I suppose. However, I had fine faith in that bomb. It is quite an effective weapon if you drop it close enough. Right beside the submarine, in the water, is best.

Those anti-aircraft bursts were giving me just a touch of headache. There wasn’t a great deal of danger from them but they were annoying. I was climbing as hard as I could and then young Merritt called over our radio. “Is the bomb armed, Mr. Dickinson?”

I was busy in my cockpit just that second and did not respond. “Mr. Dickinson, is the bomb armed?” I feel sure I must have said yes a couple of times but this kid back of me wasn’t going to have a failure on his hands. I was climbing and estimating the situation every instant. The Japs were shooting. Merritt was prompting. “Be sure the bomb is armed!” “Look here,” I said, “the bomb is armed. For God’s sake! Relax! Maybe we can get this submarine. Take my word for it, the bomb is armed.”

Those aboard ship hadn’t realized how far I had to go when I reported I was attacking. However, when I was about half way to where I was determined to get, there was a voice in my ears, asking for a report. Was I making progress? With the Jap shooting at me, with my deep concern for fear the submarine would disappear before I could lay my egg and further rasped by Merritt’s well-meant solicitude, I was in no mood to be heckled by the ship. So I told them I would report the progress of my attack as soon as I had time to drop the bomb.

I suppose the Jap’s two deck guns had fired at least twenty-five anti-aircraft shells at me. I had had him in sight for almost eight minutes. Yet he had made no attempt to submerge. All he was doing was turning to the right a few degrees. Obviously there was something wrong with him. He had been bombed once before that day. The plane from our carrier that had found him at six o’clock in the morning had dropped a bomb fairly close to him. So I believe he could not submerge. I can’t imagine a submarine skipper in his right mind staying on the surface to fight a plane rather than dive. Even when I was three or four minutes away, in good working order he might have submerged easily. He did not, so I believe that he had previously been damaged.

Those two deck guns, one forward, one aft, were big enough to sink anything but a battleship. But they were firing a couple of machine guns, too. These were mounted on the platform of the oval, tank-like conning tower. For the second time in three days I could see the head-on, deadly jewel wink of machine guns but the flashes from the muzzles of those two anti-aircraft guns were yellow as lemon cream. Nevertheless the black explosions that occasionally washed a slight tremor into the plane quite definitely were not lemon pies.

I was measuring the sub’s course, measuring my height and getting nicely set when my gunner spoke again. “Is the bomb armed, Mr. Dickinson?” This time I said, rather gently, I think, “Yes.” Then I dived. I had a pretty good dive. All the way down I could see the heathen still shooting. Their faces looked brown, not yellow. I wasn’t close enough to see expressions because I was probably as much as thirty stories higher than the Empire State building when I acted. At the left-hand side of the cockpit there is a handle, the bomb release. You simply pull this back so that it travels an inch or possibly an inch and a quarter, until it will go no further. There is no click or jar but you know you have dropped your bomb.

By the time I was able to pull out of the dive, and turn to get my plane’s tail out of the way of my eyes it was probably fifteen seconds before the bomb struck; it struck right beside the submarine, amidships.

I saw first of all only one gun was firing. I suspect the bomb explosion had killed the Japs at the other gun. In a further space of seconds I had the plane turned and was flying back towards the sub. It had stopped, had no perceptible headway and had started to settle, as nearly as I could tell, on an even keel. The fact she had no forward motion satisfied me right then this was not a dive. She was settling! A little more by the stern than forward. In about three-quarters of a minute after my bomb struck the sub had gone under the water.

The chances are, I think, that the bomb explosion caused the submarine to open up underneath. That would kill her speed. Filling amidships would cause her to settle more or less on an even keel. Right after she disappeared, from her amidships, as near as I could tell, there was an eruption of oil and foamy water, like the bursting of a big bubble. Seconds later, fifteen or twenty, I suppose, there was a second disturbance; another bubble-like eruption of foam and oil churned to the white-capped surface of the sea. This time I saw some debris. I reported to the carrier what I had done and what I had seen. But I was careful to say that “possibly” the submarine had been sunk. You simply can’t be sure on such evidence.

During the flight back to the carrier the young man in the rear seat and I discussed the probabilities. “Looks like we got him, Mr. Dickinson.” “Yes, I think we did.”

“That’s certainly pretty nice, huh?”

If you had seen Pearl Harbor you would think so, too. I said to Merritt: “Glad you didn’t let me forget to arm that bomb.”

This was no time to lose the ship but as I approached the position where I estimated she would be all I could see was a big rainstorm covering the area. I circled the storm without seeing a trace of the carrier. I felt certain she was in the storm but I had a feeling it would be easy to get lost in such weather. At such a time! I had things to talk about. I finally plunged into the rainstorm and there was the carrier.

The day proved hectic for Task Force 8 and the quarries she sought. In addition to the two bombing attacks on surfaced submarines and the sinking of I-70, there were seven other confirmed contacts with enemy submarines, which included non-stop air operations, periscope and conning tower sightings, two torpedo wakes clearly observed aiming for Enterprise, two depth charge attacks by screening destroyers, and gunfire at one submarine observed on the surface by the cruiser Salt Lake City. Throughout the day the two forces were constantly searching and maneuvering for shots at one another, or to spoil shots, weaving, zigzagging, changing speeds and directions.

The day after the loss of I-70 and Task Force 8’s heavy engagement with the Japanese submarines in the vicinity of Oahu, Vice Admiral Mitsoyoshi was aware only that he had heard nothing from the submarine’s commander, and the boat’s status was still uncertain. Nevertheless, looking ahead to operations off the West Coast of the United States, and answering to directives from Imperial General Headquarters, he issued a detailed order to the Submarine Force Detachment now moving toward the coast. On Christmas Eve night, I-15, I-9, I-10, I-17, I-19, I-21, I-23, I-25 and I-26 were to each surface and fire 30 shells on selected targets. Rear Admiral Sato, aboard I-9, was charged to execute the order.

Several facts were evident in Task Force 8’s high number of active encounters with Japanese submarines 7 through 13 December. The enemy submarines were in the waters around Oahu in force, astride the sea lanes between Hawaii and the mainland, and an unknown number were now moving toward the west coast. They would probably arrive on stations off the west coast about 17 December. Between the 10th and the 17th, the enemy would begin taking a toll on shipping.

While Enterprise and the ships and planes of Task Force 8 were aggressively pursuing enemy submarines north and northeast of Oahu on 10 December, the carrier Saratoga, which departed San Diego 0958 hours the morning of 8 December, bound for Pearl Harbor, was refueling the three destroyers in her submarine screen, one at a time. From Destroyer Division 50, they were the Talbot (DD-114), Waters (DD-115), and Dent (DD-116), all World War I “four stackers.” Saratoga, which began flight operations on the 9th, on the 11th dispatched Talbot to pick up the two-man crew from an SBD, plane number 3-B-2, from Bombing Squadron Three (VB-3). The aircraft went down 50 miles distant, and another plane in the flight reported the two men were in their rubber boat.

On 12 December at 1335 hours, Talbot, Waters and Dent, were relieved of screening duties and turned back to San Diego when the ships of Task Force 1, which had been sent by CinCPac to escort and screen Saratoga on into Pearl Harbor, took stations in the formation. The ships in the now-strengthened task force were the heavy cruiser Minneapolis (CA-36), and the newer, more modern destroyers Tucker (DD-374), Selfridge (DD-357), Case (DD-370), and Conyngham (DD-371).

Saratoga entered Pearl Harbor and moored at pier F-9 at 1037 the morning of 15 December without having logged a single submarine contact the entire sortie from San Diego to rejoin the Pacific Fleet in Hawaii. Less then twenty-four hours later, at 1226 on 16 December she was underway again, turning west southwest, soon to join Task Force 14 and deliver additional aircraft to Wake Island. At 1350 hours, while outbound initially to the southeast, Saratoga logged the sighting of Task Force 8 and the Enterprise, which was proceeding to Pearl Harbor for refueling and provisioning for further operations.

While Saratoga and her newly formed task force were en route to Pearl Harbor from San Diego, Task Force 12, with the Lexington, was returning from the cancelled delivery to Midway of 18 Marine Vought SB2U-3 Vindicators from VMSB-231 squadron at Ewa. On orders from CinCPac, Task Force 12 turned around the morning of 7 December to search for the Japanese carrier strike force while maneuvering toward Pearl Harbor. At 1152 hours, as Lexington and her screens were steaming northwest toward the harbor’s entrance, the heavy cruiser Indianapolis (CA-35) reported a torpedo wake on the cruiser’s port side and the task force began maneuvering to avoid additional torpedo launches at Lexington.

At 1621 hours, another submarine contact was reported on Lexington’s starboard bow, and she changed course left to avoid a torpedo wake that had been sighted. Escorting destroyers attacked the intruder with depth charges. Unknown to Lexington and Task Force 12, the depth charge attacks had taken their toll on the Japanese submarine I-68, whose captain was Commander Otoji Nakamura.

Ordered to patrol on a station 20 to 50 miles southwest of Pearl Harbor, Nakamura vainly attempted more than once that day to penetrate the submarine screen and torpedo Lexington. For his trouble I-68 was repeatedly hammered by 21 near miss, depth charge attacks. The attacks were uncomfortably close to being fatal for I-68 and its crew. The last attack wrecked many of the submarine’s battery cells, and caused flooding in her aft torpedo tubes. Nakamura decided to terminate I-68’s first patrol against the United States Navy, in support of the Combined Fleet’s Pearl Harbor operation, and brought his crippled submarine limping slowly back to Kwajalein, where it arrived on 28 December – a long, and undoubtedly tense 15-day journey for the crew.

Following another rapid turnaround, Lexington was again underway from Pearl at 1357 hours on 14 December, and at 1732, saw Saratoga and her task force disappear over the horizon as she returned to refuel, take on aviation fuel and provisions, for the next sortie. Steaming on a southwesterly course as part of Task Force 11, by shortly after midnight the morning of 17 December, Lexington and the commanders of all the task force’s ships knew they were embarked on a raid on the Japanese-held Marshall Islands, in support of Saratoga’s planned delivery of additional aircraft to Wake Island.

Saratoga left Pearl on 16 December, steaming toward the west, southwest with four destroyers providing plane guard duties and submarine screen: the destroyers Blue (DD-387), Henley (DD-391), Helm (DD-388), and Bagley (DD-386). At 1215 on 17 December, she commenced joining Task Force 14, a powerful force consisting of the heavy cruisers San Francisco (CA-38), Astoria (CA-34), and Minneapolis; destroyers Mugford (DD-389), Selfridge, Patterson (DD-392), and Ralph Talbot (DD-390); the tanker Neches (AO-5) and seaplane tender Tangier. Finally, Lexington and Task Force 11, supporting Saratoga and Task Force 14 were about to take the fight to the enemy.



Japan’s Panama Canal Buster II

In December 1944, the Imperial Japanese Navy organized the 1st Submarine Flotilla and 631st Kokutai (Air Corps), with Captain Tatsunoke Ariizumi commanding both units. The force consisted ofI-400, I-401 and two AM-class subs, I-13and I-14, which were smaller and carried two Seirans each, for a total of 10 Seiran bombers. An experienced naval officer from a distinguished military family, Ariizumi and had been in charge of the midget sub attacks at Pearl Harbor.

In March 1945, Vice Adm. Jisaburo Ozawa, vice chief of the navy general staff, toyed with a plan to use the Seirans to unleash biological weapons on a U.S. West Coast city in revenge for the firebombing of Tokyo. The notorious Japanese Unit 731 had already conducted successful experiments in Manchuria using rats infected with bubonic plague and other diseases to kill Chinese citizens. But the opera­tion was canceled later that month by General Yoshijiro Umezu, chief of the army general staff, who declared, “Germ warfare against the United States would escalate to war against all humanity.” Instead, the Japanese decided to target the Panama Canal.

By 1945 there was little doubt among the Japanese that the war was going badly. If Germany was defeated, the Allies would be on their doorstep next. The Panama Canal was a major transshipment point for war materiel essential to the Pacific theater. Closing it off would slow down if not stop the Allied advance, which would give Japan much-needed breathing room. As a result, the plan to at­tack the canal, drain Gatun Lake and block Allied shipping made strategic sense.

Japanese engineers had helped to build the canal, so Japan had construction plans to work from. Since Japanese carriers couldn’t get close enough to at­tack without being discovered, the 1st Sub­­marine Flotilla and 631st Koku-taiwere selected for the task.

The four submarines were to leave Japan in June 1945 and surface 100 miles off the coast of Ecuador, where they would launch their 10 Seirans at night. The Seirans, painted to resemble U.S. Army Air Forces planes, would fly northeast over Colombia, turn west over the Caribbean, then attack from the north at dawn, torpedoing the Gatun locks. After returning to their launch point, the pilots would ditch their planes and swim to their respective subs.

Before I-400 and I-401 crews could begin training for the mission, however, the Japanese had to deal with a severe fuel shortage resulting from the Allies’ sinking their tankers. The I-400s did not have enough die­sel to complete their mission, soI-401, disguised as a frigate with a false funnel, was ordered to Manchuria to get more fuel. On April 12, shortly after departure, the sub was damaged by a mine and had to return to port for repairs, but I-400was sent in its place and returned with the necessary fuel.

By June 4, the sister subs had arrived in Nanao Bay for battle training. There the crews practiced speeding up the assembly of the Seirans, night catapult launches, and submerging and surfacing the submarines in preparation for launches.

“The sub’s pitching and rolling made catapult launches difficult; the navigator had to time it just right,” Lieutenant Asamura remembered. “Nevertheless, compressed air made it a smoother launch than catapults that used gunpowder.” Asamura also recalled the importance of launching against the wind to make sure the Seiran got enough lift. As a result, he said, “It could be dangerous if the wind direction changed on you during a catapult launch.”

A full-scale mockup of the Gatun locks was constructed to practice Seiran torpedo runs, but training conditions proved ex­tremely difficult. The I-400s had to deal with relentless Allied bombing and strafing as well as heavily mined waters. There were not enough experienced pilots for the mission, and two Seirans were lost during training. In fact, only one pilot had the requisite torpedo experience, so it was decided the Seirans would carry a single large bomb instead of a torpedo. To ensure success, the pilots would fly their aircraft directly into the locks rather than risk inaccurate bomb drops.

Born in Osaka in 1922, Asamura now lives in Tokyo’s Nezu section in a high-rise apartment with his wife. A small, balding man, he has an interest in history and a fair understanding of English.

Asamura remembered that for the pilots, “life on a submarine was 180 degrees different than flying in the air. You couldn’t tell night from day on the sub, so I never knew what meal I should be eating.” But he also noted that though they ate canned rather than fresh food, there was enough to go around, which often wasn’t the case for the Japanese army. Pilots had no duties to perform on the sub, and he recalled that crew relations were good.

Asamura said the Panama Canal mission was an open secret among I-401‘s crew. But with the U.S. already positioning an enormous armada of ships, aircraft and troop transports in the Pacific for the planned invasion of Japan, the Japa­nese navy’s high command decided the Seirans should attack U.S. carriers at Ulithi Atoll instead of the canal.

Captain Ariizumi was disappointed that the Panama mission had been canceled and argued the decision with his superior officers. Accord­ing to Captain Zenji Orita in his 1976 book I-Boat Captain, Ariizumi was told, “A man does not worry about a fire he sees on the horizon when other flames are licking at his kimono sleeve!”

Asamura recalled that he was not disappointed at the change in mission objective despite the intensive preparation because he knew the situation. “I understood the importance of the Panama mission, but the U.S. was on our doorstep and that was more imperative,” he said.

I-400 and I-401received orders on June 25 for a two-part operation. The first phase was called Hikari (light). I-13 and I-14were to offload four Nakajima C6N1 Saiun reconnaissance aircraft at Truk Island, where the planes would scout the American fleet at Ulithi and relay target information to I-400 and I-401. The second part of the operation, called Arashi (storm), involved the twoI-400 subs launching their six Seirans to carry out kamikaze attacks on the U.S. carriers and troop transports in coordination with Kaiten (manned torpedoes).

Fake U.S. markings were applied to the Seirans on July 21, and two days later I-400 and I-401 set out following separate routes to reduce their chance of discovery. The mission, however, was plagued by problems. En route, a Japanese shore battery accidentally shelled I-401, and I-13, carrying two of the Nakajima surveillance planes, was sunk, most likely by an American destroyer. Ad­ditionally, I-400failed to pick up a crucial radio message, which led to its missing its rendezvous with I-401. As a result, the attack was postponed until August 25, giving the two subs time to regroup.

I-401‘s Commander Nambu recalled picking up Allied broadcasts on August 14 an­nouncing that Japan would soon surrender, but he did not believe them at the time, assuming they were either propaganda or a trick. Even when Emperor Hirohito made his August 15 radio broadcast asking the Japanese people to “endure the unendurable,” the captain and lieutenant commander debated whether to continue the mission, return to Japan or scuttle the ship. Asamura said he missed the emperor’s surrender announcement because he was sleeping at the time, but was not surprised that Japan had to surrender as he knew the war was going badly.

Some of I-401‘s crew wanted to go ahead with the plan to attack U.S. forces at Ulithi. In fact Nambu said that even after I-401 received specific instructions canceling the operation and ordering the sub back to Japan, some crew members wanted to keep the sub and become pirates instead.

Finally, I-401‘s crew hoisted the black triangular surrender flag and on August 26 fired all of its torpedoes. The crew destroyed its codes, logs, charts, manuals and secret documents, and after punching holes in the Seirans’ floats, either pushed or catapulted them into the sea. I-400 surrendered on August 27 on its way back to Japan, and two days later I-401encountered USS Segundo.
Captain Ariizumi appointed Lieutenant Bando, I-401‘s chief navigator, to negotiate the surrender of his flagship to Segundo, in part because Bando spoke some English. Despite the Japanese navigator’s English training, however, Commander Johnson wrote in his war patrol report that he and Bando “held a doubtful conversation…in baby talk plus violent gestures.”

Johnson initially responded with disbelief to Bando’s assertion that I-401carried 200 men, stating, “This could quite possibly be an error on his part, as I think the war interrupted English instruction.” But of course Bando’s figure was correct.

Bando remembered Captain Ariizumi becoming impatient with the surrender negotiations, preferring to scuttle the submarine and have the officers and crew commit suicide. Johnson was also concerned about the possibility of mass suicide aboard the sub, but after some haggling, terms were agreed upon and a prize crew from Segundo boarded I-401, checked that there were no torpedoes left, chained the hatches open to prevent the sub from diving and accompanied it on its return to Japan.

At 0500 hours on August 31, the U.S. flag was hoisted aboard I-401and Commander Nambu delivered two samurai swords as a symbol of surrender to Lieutenant J.E. Balson, Segundo‘s executive officer and prize crew chief. Shortly thereafter, Ariizumi shot himself in his cabin with a pistol; his body was subsequently buried at sea. “It was a small boat,” Asamura said. “Everyone knew the commander had killed himself.”

Nambu recalled that the officers and crew of I-401“received gentle treatment by the U.S. Navy after the surrender.” Bando noted that Johnson even invited him to visit the United States after the war.
Escorted by Segundo, I-401sailed to Yokosuka in Tokyo Bay, where it officially surrendered to the U.S. The sub was stricken from the Imperial Japanese Navy’s active duty roster on September 15.

The I-400 submarines only saw eight months of service from their launch to their surrender, and the Seirans likely never flew in combat. But the U.S. Navy was so impressed by the underwater aircraft carriers that it decided the subs merited further study. On December 11, 1945, I-400and I-401 sailed with an American prize crew of four officers and 40 enlisted men (as well as a load of smuggled Japanese war souvenirs in I-400‘s hangar) from Yokosuka to Pearl Harbor. They were escorted by a sub rescue vessel, and after an uneventful trip arrived in Pearl on January 6, 1946.

According to the late Thomas O. Paine, who served as executive officer and navigator during I-400‘s trip to Pearl Harbor, the absence of manuals for the I-400s did not stop American crews from figuring out how to operate the subs because “Japanese submarine design…followed fairly standard practice.” In an unpublished memoir, Paine wrote that the prize crews developed their own drawings and color codes for I-400‘s operating systems as well as “learned under the critical eyes of Japanese petty officers.”

Paine explained that I-400‘s interior included a “large torpedo room, chief’s quarters, radio shack, capacious wardroom featuring fine wooden cabinet work, a Shinto shrine, officer’s staterooms, and a large control room.” He also described the sub’s aft crew compartment as having “raised wooden decks polished like a dance floor—you took your shoes off before walking there.”

Both subs were extensively studied at Pearl, though the Navy never tried submerging either one. When the Soviets asked for access to the I-400s as part of an information-sharing agreement, U.S. officials decided to prevent them from obtaining potentially disruptive technology by scuttling the submarines. I-402 was sunk off Japan’s Goto Island in April 1946, and I-401 was tor­pedoed by the submarine Cabezon and sunk off Pearl Harbor on May 31. I-400 quickly followed it to the bottom.
In March 2005, the Hawaii Undersea Re­search Laboratory, using two deep-diving submersibles, located I-401 off the coast of Kalaeloa in 2,665 feet of water. The main hull sits upright on the bottom. The bow is broken off just forward of the airplane hangar, and the “I-401” designation is still clearly visible on the conning tower. Otherwise the sub appears in remarkably good condition. I-400 and I-402 have yet to be found.

Nambu, who knows that his old sub command has been rediscovered on the ocean floor, believes I-401 and its Seirans comprised a strategic weapon. But though he feels the Panama Canal bombing mission was an objective worthy of his flagship sub, he thinks the mission would have needed to occur at least a year earlier than planned in order to be truly effective.

Some reports have suggested that the I-400 submarines’ technology was incorporated into future U.S. submarine innovations like the Regulus sub-launched missile program, much as Wernher von Braun’s V-2 program became the backbone of future U.S. ballistic missile and space programs. Though this may give the technology more credit than it warrants, the underwater aircraft carriers were clearly superior in important ways to subs at the time.

And though Nambu is proud of what he accomplished in defense of his country, he feels Japan did not make full strategic use of submarines during World War II. “Subs were not meant to be deployed as cargo carriers,” he said, referring to the many missions in which submarines were used to provide supplies to the Japanese army on remote island outposts. “Subs were meant to attack.”

Fortunately for the United States, I-401 and its Seirans never got the chance.

John Geoghegan, who frequently writes about marine and aviation adventure and exploration, is a director of the SILOE Research Institutein Marin County, Calif. Additional reporting for this article was done by Takuji Ozasayama. Further reading: I-400: Japan’s Secret Aircraft-Carrying Strike Submarine, by Henry Sakaida, Gary Nilaand Koji Takaki.

Japan’s Panama Canal Buster I


Members of the US Navy inspecting the plane hangar of I-400.

It was seven minutes before midnight on August 28, 1945, when a large unidentified object appeared on the radar screen of USS Segundo, a Balao-class submarine on patrol south of Japan. It had been 13 days since Japan’s sur­ren­der an­nounce­ment, and Segundo‘s commanding of­fi­cer, Lieu­tenant Commander S.L. John­son, was on the lookout for remnants of Japan’s naval fleet. Segundo was 18 days out from Midway, and except for an en­coun­ter with a Japanese fishing boat, the patrol had been uneventful.

Soon after Segundo changed course to intercept the blip, Commander Johnson and his men realized they were on the trail of a Japanese submarine. After tracking the sub for more than four hours, Johnson tired of the cat-and-mouse game and radioed for it to stop, receiving a positive acknowledgement in reply. But as Segundoclosed in, Johnson and his crew were literally in for a big surprise.

The vessel 1,900 yards off their bow was not your average Japanese submarine; it was I-401, flagship of the I-400class known as Sen-Toku, or special submarines. At the time I-400s were the biggest submarines ever built, and they would remain so for nearly 20 years after the war. The sub Commander Johnson intercepted simply dwarfedSegundo.

Johnson and his men were about to discover that they’d happened upon one of the war’s most unusual and innovative weapon systems. Not only was I-401bristling with topside weaponry, the sub was also designed to carry, launch and retrieve three Aichi M6A1 Seiran floatplane attack bombers. In other words, I-401wasn’t just a major offensive weapon in a submarine fleet used to playing defense—it was actually the world’s first purpose-built underwater aircraft carrier.

Japan’s I-400 subs were just over 400 feet long and displaced 6,560 tons when submerged. Segundo was nearly 25 percent shorter and displaced less than half that tonnage. Remarkably, I-400s could travel 37,500 nautical miles at 14 knots while surfaced, equivalent to going 1½ times around the world without refueling, while Segundo could travel less than 12,000 nautical miles at 10 knots surfaced. I-400s carried between 157 and 200 officers, crew and passengers, compared to Segundo‘s complement of 81 men.

Originally conceived in 1942 to attack U.S. coastal cities, the I-400subs and their Seirans were central to an audacious, top-secret plan to stop the Allies’ Pacific advance by disguising the floatplane bombers with U.S. Army Air Forces insignia and attacking the Panama Canal. It was a desperate, Hail Mary–type mission to slow the American advance in the closing days of World War II. However, when the giant subs were finished too late in the war to be effective in stemming the Allied tide, they were reassigned to attack U.S. carrier forces at Ulithi Atoll, the launch point for a devastating air campaign against Japan in preparation for Operation Olym­pic, the planned invasion of the island nation.

But Commander Johnson and his men did not know any of this at the time because the United States was unaware that Japan had underwater aircraft carriers and knew little about its powerful attack bombers. As a result, when Johnson got a good look at I-401, he marveled at the “latest thing in Jap subs.”

After I-401 and its sister sub, I-400, surrendered in August 1945, U.S. officials were similarly staggered by their size, long-range capability and ability to carry and launch floatplane bombers. The Allies had nothing comparable in their fleet. Had the I-400s been built just six months earlier and succeeded in their mission, they could have thrown a major wrench into the Allied advance, giving Japan valuable time to regroup and rearm.

The Smithsonian National Air and Space Museum, which has restored the last surviving Aichi M6A1 (see “Re­stored,” P. 58 in the print version of Aviation History, May 2008 edition), calls the I-400–class subs and their Seirans “an ingenious blend of aviation and marine technology.” In other words, it was a state-of-the-art sub with a similarly sophisticated plane designed to inflict serious damage.

The I-400s boasted a maximum speed of 18.75 knots surfaced, or 6.5 knots submerged. They could dive to a depth of 330 feet, shallower than most U.S. subs at the time, and had a draft of 23 feet—fairly deep but hardly surprising given the sub’s size.

Nevertheless, the I-400s were to submarines what the Yamato class was to battleships. They carried Type 95 torpedoes, a smaller version of the Type 93 Long Lance torpedoes, the most advanced used by any navy in the war. The oxygen-powered 95s traveled nearly three times farther than the American Mark 14s, carried more explosive punch, left virtually no wake and were the second fastest torpedoes built during the war (Type 93s were the fastest). They were launched from eight 21-inch forward torpedo tubes, four on each side (two upper and two lower). Unlike U.S. subs, I-400s had no aft torpedo tubes, which could prove a shortcoming in certain situations, but topside they were all business, with one 5.5-inch rear- facing deck gun, three triple-barrel 25mm anti-aircraft guns on top of the aircraft hangar and a single 25mm gun on the bridge.

The most innovative aspect of the I-400 subs, however, was their role as underwater aircraft carriers. Each packed three Seirans in a huge, 115-foot-long watertight hangar that projected from the bridge structure onto the deck. The hangar was so large that the conning tower had to be offset seven feet to port of centerline to accommodate it. The hangar in turn was offset two feet to starboard to compensate for its size. A massive hydraulic hangar door opened onto a 120-foot-long compressed-air catapult that launched the Seirans. A collapsible hydraulic crane lifted the planes back on board for hangar storage. It was the unusual, bulbous shape of I-401‘s hangar that especially captured the interest of Johnson and his men.

In a recent interview at his son’s home outside Tokyo, Lt. Cmdr. Nobukiyo Nambu, who captained I-401, said the I-400subs were maneuverable for their size. “I-401‘s maneuverability under the sea was no different than other subs, though it had a greater turning radius on the surface,” recalled the 97-year-old, who is surprisingly tall for a submarine captain and still maintains an erect bearing.

Born in 1911, Nambu is a living history lesson. Though he walks with a cane and is hard of hearing, he recently authored a successful book about his adventures aboard I-401. His navy career began with a scholarship to Eta­jima, Japan’s naval academy, attending submarine school and graduating as a member of class number 62. Nambu served as the chief torpedo officer on I-17 during the Pearl Harbor attack and later shelled Santa Bar­bara, Calif., in February 1942, an incident that became the basis for Steven Spielberg’s movie 1941. After the war he served in Japan’s Maritime Self Defense Force, achieving the rank of rear admiral.

Lieutenant Muneo Bando, Nambu’s chief navigator and a sometime observer aboard a Seiran, remembered I-401 as harder to navigate than a smaller sub. He said the big boat required one kilometer to stop and the crew experienced a 30-second delay in re­sponse to steering commands. But I-400s gained a reputation for riding smoothly in rough seas due to their double hull construction—essentially two large steel tubes laid side by side.

The I-400s were specifically designed as underwater aircraft carriers to support the M6A1 Seiran, designed by Aichi’s chief engineer, Toshio Ozaki, and built in the company’s Nagoya factory. The Seiran was intended to strike directly at the U.S. mainland. Unlike previous sub-based aircraft designed for reconnaissance or defensive measures, it was a purely offensive weapon built to command respect.

In the book I-400: Japan’s Secret Aircraft-Carrying Strike Submarine, Lieutenant Ta­dashi Funada, a test pilot who flew the first Seiran prototype, is credited with naming the aircraft. The name Seiran is composed of two Japanese words that can be translated as “storm out of a clear sky.” According to the authors, Lieutenant Funada’s hope was that the bomber would gain the key element of surprise by suddenly seeming to appear out of nowhere.

Aichi completed the first Seiran prototype in the fall of 1943, and the Imperial Japanese Navy was happy enough with the result to order production to start immediately. The original production goal of 44 aircraft was eventually reduced to 28 (including two M6A1-K trainers) due to the plane’s cost and war-driven material shortages, not to mention two major earthquakes and relentless bombing by B-29s, both of which damaged Aichi’s Seiran factory.

Former Lieutenant Atsushi Asamura, the leader of Squadron Number 1, which was re­sponsible for the planned attack on the Panama Canal, confirmed the difficulties surrounding Seiran production. Interviewed in his Tokyo apartment, the 86-year-old former pilot said, “The Seirans that were custom built were of good quality, but as they scaled back production the quality became poor due to material shortages and difficult manufacturing conditions.” In fact, many of the Aichi employees responsible for building the Seirans were high school students.

Nevertheless, Lieutenant Asamura, who remains fit and speaks in a strong voice, recalled the Seiran as “a good performance aircraft,” confirming its reputation as streamlined and responsive, with excellent attack power. “It was a versatile plane since it was both an attack bomber and had long distance range,” Asamura said, illustrating the Seiran’s easy handling by holding his arms out like wings, then grabbing an imaginary stick. “But there was no big difference in how it handled a sea landing compared to other planes.”

Asamura also recalled that the Seiran’s liquid-cooled engine provided pilots with much better visibility than the bulkier and more common air-cooled engines in use at the time. The Atsuta 30 series 12-cylinder inverted Vee engine (Japan’s version of a German Daimler-Benz DB 601A) delivered 1,400 hp, and its liquid-cooled design meant it didn’t need as much warm-up time as an air-cooled engine, so the plane could launch faster. Given the danger subs faced on the surface, this was a distinct advantage.

The Seiran featured a metal frame construction with a riveted metal fuselage and triple-blade propeller. It required a crew of two: a pilot and an observer who sat in a tandem configu­ration. The observer served as radio operator and navigator, also manning the flexible rear-facing 13mm machine gun, which flipped up from a recess in the fuselage and locked into place for firing. The aircraft carried either a 551-pound bomb with its floats attached or a 1,764-pound bomb (or torpedo) without floats. The heavier ordnance meant that the pilot would have to ditch the plane upon his return, or it was a one-way suicide mission.

By necessity, the Seiran had hydraulically folding wings similar to the Grumman F6F Hellcat’s that rotated 90 degrees to ensure the aircraft fit inside its small, tubelike hangar, which was only 11 feet 6 inches in diameter. Part of the horizontal stabilizer and the tip of the vertical stabilizer also folded down to accommodate the tight fit. The plane’s floats were detachable and stored separately, as were their support pylons and spare parts.

One of the key requirements of the Seiran was that it could be rolled out on a dolly, assembled by its ground crew and launched in a very short time. Reports vary on how fast this could be accomplished. According to Commander Nambu, intensive training enabled the I-401 crew to launch three planes within 45 minutes. But Nambu also noted that given the rough handling the Seirans received during sea launches and landings, it was difficult to keep all three in good operating condition at the same time.

The Smithsonian notes the Seirans had “interesting design features built in…that ranged in engineering quality from the ingenious to the seemingly absurd.” The fact that some of the floatplane’s parts were painted with luminescent paint for night assembly certainly has to fall into the former category. Lieutenant Asamura claimed the Seiran cost “50 times more than a Zero to produce,” and though it’s not possible to confirm the exact cost, clearly they were expensive to manufacture.

Although some German and British subs had carried reconnaissance aircraft on their decks during World War I, Japan was the only nation to use submarine-launched aircraft in WWII. At the beginning of the war, it had approximately 63 oceangoing subs, 11 carrying one catapult-launched reconnaissance plane each. Even­tually, Japan would expand this to a total of 41 aircraft-carrying subs.

Admiral Isoroku Yamamoto, commander in chief of the Combined Fleet and architect of the Pearl Harbor attack, gets credit for the I-400class of submarines and its Seiran bomber, though I-401‘s Commander Na­mbu says the actual idea for an underwater aircraft carrier probably originated from lower down in the command structure. Admiral Yamamoto’s vision in 1942 was for the underwater aircraft carriers to launch their Seiran attack bombers against U.S. coastal cities such as Washington, New York, San Francisco and Los Angeles, to deliver a Doolittle-like blow to American morale.

The original plan was to build 18 I-400– class subs, but after Yamamoto was ambushed and killed by Lockheed P-38 Lightnings in April 1943, the guiding hand behind the I-400subs was gone. Construction plans were scaled back to nine subs, due in part to steel shortages. Actual construction began on five subs but was later reduced to three, of which only two (I-400 and I-401) made it into service. A third, I-402, was converted into a fuel tanker and completed in July 1945 but never saw active duty.

Final design plans for the underwater aircraft carriers were finished by May 1942, and construction on the first sub (I-400) began at Kure’s dockyards in January 1943. I-401‘s construction quickly followed. By December 30, 1944, I-400was complete, and I-401 was completed less than two weeks later. Both subs immediately deployed for their shakedown cruises.

Operation K

Less than three months after the gigantic Japanese aerial and submarine onslaught against Pearl Harbor a second, considerably more modest, raid on the US Pacific Fleet’s anchorage was mounted by the Imperial Navy. Although nothing more than a ‘nuisance raid’, the logistical planning required to strike once again at American soil demonstrated the excellent Japanese use of aircraft and submarines working in close cooperation. Submarines were destined to play a crucial role in the operation, codenamed ‘K’, and much more effectively than the suicidal midget submarine attacks of December 1941.

The Japanese devised a plan to use a pair of newly introduced Kawanishi H8K1 four-engine naval flying boats of the 24th Air Flotilla to strike Oahu.7 These aircraft, given the codename ‘Emily’ by the Allies, had a maximum range of 3,040 miles and were able to haul one ton of bombs. They were a Japanese equivalent of the famous British Short Sunderland, though larger (incidentally, before the war the Kawanishi company had had a close working partnership with Belfast-based seaplane manufacturers Short Brothers). The plan would see both of these huge aircraft, each with a crew of ten, fly from a starting point at Wotje Atoll in the Marshall Islands to a midway point and rendezvous position at the remote French Frigate Shoals located 482 miles from Pearl Harbor. The submarine I-9 was ‘assigned to take up station midway between Wotje and the Shoal and act as a radio beacon’8 for the two flying boats. At French Frigate Shoals the pair of flying boats would meet two large Japanese submarines that would be waiting for them inside the protected lagoon. The two submarines selected for the primary part of the mission were the I-15 and I-19 respectively, both boats normally being fitted with the tiny two-seater Yokosuka E14Y1 floatplane for reconnaissance in a watertight hanger in front of the conning tower. For the purposes of Operation K the planes were removed and replaced with ten tons of aviation fuel in drums on each submarine, packed inside the hangar space for safe transit to French Frigate Shoals. After the arrival of the flying boats the two submarines would replenish the planes’ fuel tanks before the Kawanishi’s set off on the final leg of their outbound mission to Oahu. As a backup, should either of the two submarines be lost, the I-26 was directed to shadow the pair and act as a reserve fuel tanker, and also to act as a picket to constantly scan for any enemy activity in the vicinity.

The submarine I-23, under Lieutenant-Commander Genichi Shibata, had a more hazardous task to perform, which required her to creep as close as ten miles from the coast of Oahu and report on weather conditions over the target. Additionally, should either or both of the flying boats be shot down during the run over Pearl Harbor, the I-23 was to attempt to rescue any downed aircrew.

The Kawanishi H8K1 was also nicknamed the ‘Flying Porcupine’, and for good reason. Mounted in turrets and blisters around the aircraft were five 20mm cannon and four 7.7mm machine guns, making it a dangerous quarry for any roving Allied fighter to tackle. A pair working in close cooperation, and covering one another with their guns would be more concerned about ground anti-aircraft fire than fighter interception.

The Japanese selected 1 March 1942 as the day of the attack, and all submarines taking part in the operation were expected to be in position one day before the flying boats showed up. The I-15 and I-19 sailed imperiously into the lagoon at French Frigate Shoals at the assigned time, deck-guns fully manned in case American lookouts or coast watchers had been planted on the islands. Lieutenant Toshi Hashizume and Ensign Tomaro had been selected as the pilots of the respective Kawanishi’s, and they departed from Yokosuka harbour in Japan on 15 February and began the long journey to the mission jumping-off point. The flight plan took them first to Saipan in the Marianas, then the big Japanese naval base at Truk in the Carolines, and on to Jaliut in the Marshall Islands before they splashed down at Wotje Atoll. Weather was the all-important factor determining when the mission actually began, and information about the weather over Oahu came to the Japanese from two different sources. Firstly, they had cleverly cracked the local weather reporting code used by US naval air stations at Midway Island, Hawaii and Johnson Atoll. The second source would come from the submarine I-23, positioned ten miles to the south of Oahu. Unfortunately, just as the Japanese were gearing up to launch the mission all information concerning weather ceased. Two things had occurred which meant a delay in launching the aircraft on their way to Pearl Harbor. The first was a routine change in the code being used by the US Navy to report weather conditions over their airfields in the region, leaving the Japanese outside of the information loop. The other was the sudden loss of contact with the I-23, Radio communications emanating from the Japanese were also being picked up by the Americans, indicating to them that there was Japanese submarine activity in the area of French Frigate Shoals, ‘…so the Americans, centered on the Naval Combat Intelligence Unit at Pearl Harbor, broke Japanese naval codes, enabling them to ascertain the whereabouts of Japanese surface and submarine assets’.9 The sudden loss of contact with the I-23 was ominous, and, according to Hackett and Kingsepp, the Japanese Navy presumed the submarine lost with all hands on 28 February off Hawaii.

One of the principal Japanese naval bases in the Western Pacific, located at Rabaul in New Britain, now found itself menaced by an American naval task force that was discovered to be steaming towards the base as weather reports ceased, and the mission began to look in doubt. The task force, built around the aircraft carrier USS Lexington, appeared a juicy target to the Imperial Fleet’s local headquarters at Truk, and all available submarines and surface warships headed out and searched for the force. The two days spent on attempting to locate and attack the American task force, which aborted a projected attack on Rabaul, meant that the Pearl Harbor raid itself was delayed until 3 March. In the early evening the two big flying boats touched down safely in the lagoon at French Frigate Shoals, and the crews of the I-15 and I-19 set to work refuelling the huge beasts. At 9.38 p.m., both aircraft had lifted off and turned towards Pearl Harbor, the crews readying themselves for the daring strike against a location still clearing up the detritus and wreckage from the first Japanese raid, and a place maintaining a much better surveillance of the skies and seas around Hawaii, determined not to be caught out again by a sudden ‘surprise’ attack.

US Navy intelligence officers had spent the remainder of 3 March pondering the significance of Japanese submarine activity at French Frigate Shoals that had arrived on their desks from the decrypts of Imperial Navy radio communications. The officers remained unsure as to what it signified, and more importantly, whether such activity posed a threat to local American forces. The massive raid of 7 December 1941 against Pearl Harbor had been launched from Japanese aircraft carriers, and none were believed to be near to Hawaii in March 1942. No land-based Japanese aircraft had the range to reach Hawaii from the furthest regions of the Japanese Empire, and although the officers were aware that some of the larger Japanese submarines certainly mounted a small plane onboard, they also knew that the aircraft was essentially a harmless reconnaissance model that they had codenamed ‘Glen’. For the moment, the reports of enemy submarine activity remained routine, and no alarms were raised or the alert status at Pearl Harbor brought up a notch.

The pair of Kawanishi flying boats continued to devour the miles between the Shoals and a blacked-out Oahu, oblivious to the radar beams that constantly scanned the skies around the Hawaiian Islands. A US Army radar station at Kauai was the first section of the airborne early warning system to record a possible problem. At 12.14 a.m. on 4 March the radar ‘painted’ a single target moving towards Oahu at a range of 240 miles. The soldiers immediately informed the Air Raid Defense Center, who in turn telephoned the local Army Air Corps and US Navy air stations throughout the islands requesting that any friendly aircraft airborne be reported to the centre, and so could be eliminated from the air defence equation. Both the army and the navy replied that they had no aircraft then airborne, so the unidentified radar target was deemed most likely hostile.

Unlike on the morning of 7 December 1941, this time the Americans responded quickly and efficiently to the threat they now perceived to be fast approaching. At 12.43 a.m. the air defence commander ordered general quarters, bringing all military and civil defence personnel to full readiness of an impending air raid on Oahu. At 1.15 a.m. a trio of US Navy PBY Catalina flying boats took off with orders to seek out any Japanese aircraft carriers lurking close to the islands that would explain the presence of enemy aircraft bearing down on Pearl Harbor. Four Curtiss P-40 Warhawks formed local air defence, and these fighters were scrambled at 1.36 a.m. to form a Combat Air Patrol (CAP) over Pearl Harbor with orders to intercept and shoot down any hostile aircraft encountered. This was easier said than done, as the Americans lacked any dedicated night fighters, and as the P-40s were bereft of radar the pilots would have to hunt by following ground directions and using their eyes. Although originally the night had been clear, with a full, bright moon, the weather had rapidly deteriorated, and rain and clouds were now building up over the intended Japanese target. The rain that would prevent the P-40s from discovering the Japanese flying boats that night also prevented the two amphibious bombers from satisfactorily locating their targets.

The two pilots, Hashizume and Tomaro, planned to deposit their bombs over the central Ten-Ten Dock at Pearl Harbor, but as the two Japanese planes made landfall at the extreme western tip of Oahu and headed inland across the Koolau Mountains at 15,000 feet, both pilots noticed the clouds and rain squalls building up ahead of their machines. The Japanese planes stuck to an easterly course that would take them to the north of Pearl Harbor. Once close to the harbour the amphibians would make a sharp turn to port and head south to begin their bombing runs over the base. Lieutenant Hashizume’s aircraft followed the set course and arrived over the harbour as planned, but the target was badly obscured by cloud cover. Some members of his crew yelled over the intercom that they had seen Ford Island in the centre of the Pearl Harbor naval base through breaks in the cloud, but Hashizume decided to fly on, make a turn, and come back for a second look before releasing his bombs. The pilot banked the huge aircraft round to port and started back for his bomb run, dropping his payload at 12.10 a.m. through the clouds. These bombs rained down on some trees carpeting the slopes of Mount Tantalus behind Honolulu, six miles from Pearl Harbor. Four booming explosions echoed off the hills to mark the arrival of the Japanese, though hardly a soul registered the detonations as having a Japanese origin.

The second aircraft, with Ensign Tomaro at the controls, did no better than Hashizume. When Hashizume had made his sharp turn to port designed to bring him back over the target, Tomaro had misunderstood Hashizume’s order and had carried on following the southern route. Realizing his mistake with the disappearance of his wingman, Tomaro hauled the big flying boat around and retraced his path back north. At 12.30 a.m., unsure of his exact position but believing himself to be over Pearl Harbor, Tomaro released his bombs, which fell harmlessly into the sea. Both Kawanishi’s now formed up and headed away from the islands with all possible haste, leaving the P-40s and Catalinas to search fruitlessly for them.

Hashizume’s aircraft had completed the mission with a punctured hull, and this aircraft headed straight for Jaluit for repairs. Tomaro took his plane to Wotje Atoll, arriving at 2.45 p.m. Both pilots wrote detailed reports of their sorties over Oahu, and both men concluded correctly that the level of damage they had inflicted on the naval base was difficult to determine, owing to the weather conditions they had encountered over the target. Back at Pearl Harbor, to begin with the four explosions that had been heard on Mount Tantalus were investigated. The Americans initially thought that one of their own aircraft from either the army or the navy had dumped its bomb load in the countryside before landing, but closer examination of bomb fragments recovered from the scene revealed them to be of Japanese manufacture. An even more extraordinary answer to the riddle of how the Japanese had carried out the daring long distance attack slowly revealed itself, an interesting case of life imitating art.

American intelligence had suppressed a short story written by a serving naval officer in 1940 entitled Rendezvous.10 The story, by W.J. Holmes, then a lieutenant, told of a fictional American raid on a Japanese base. In the story, the Americans plan to bomb Japanese preparations for an amphibious operation by using flying boats. Because the flying boats lack the range to reach Japan from Hawaii, three submarines are used to refuel the aircraft at the fictional ‘Moab Atoll’ located 1,000 miles from Japan. The American submarines carried not only aviation fuel for the thirsty flying boats, but the bombs that they would drop on the mythical port of ‘Bosoko’ in the raid. The Office of Naval Intelligence had suppressed the story in November 1940, but after Holmes defended his right to publish using examples of similar British and Italian seaplane operations, the navy relented and Rendezvous appeared in the August 1941 edition of the Saturday Evening Post. Following the Japanese raid on Pearl Harbor in March 1942, Rear-Admiral Edwin Layton, chief intelligence officer to the commander-in-chief of the US Pacific Fleet, Admiral Chester W. Nimitz, disclosed that the Japanese had most probably copied the idea for the raid from Holmes’s short story, supplanting ‘Moab Atoll’ for the very real French Frigate Shoals as a refuelling waypoint. In the story Rendezvous the Americans manage to wreck the Japanese ships assembling in ‘Bosoko’ harbour for an amphibious attack. In the real mission, the Japanese failed to cause any damage, apart from digging up some trees.

The Americans looked carefully at Holmes’s story, and decided in light of the recent attack to dispatch the destroyer USS Ballard to the French Frigate Shoals to take a careful look, and leave behind some mines should any Japanese submarines have returned. They never did, and the evident failure of so complex an operation, including the use of three fleet submarines that would have been better employed elsewhere, meant that the Japanese would not attempt another operation of this sort again.

Steel Coffins: 7 December 1941 Part I

Mounted on the after deck of the “mother” submarine I-24, mini submarine HA-19 is boarded by its crew, Kazuo Sakamaki and Kiyoshi Inagaki, in the pre-dawn hours of December 7, 1941. Painting by Tom W. Freeman

On 28 November 1941 the Japanese First Special Attack Flotilla, consisting of the submarines I-16, I-18, I-20, I-22 and I-24, each carrying a single Type-A midget submarine clamped to the deck abaft the conning tower, began their journeys across the north Pacific to Hawaii. Aboard the I-22 was Captain Hanku Sasaki, commanding the flotilla, and he had issued orders that the submarines were to maintain a twenty-mile gap between one another as they journeyed across the ocean. Once out of Japanese territorial waters each submarine skipper informed the crew of their mission, and the purpose of the strange cargo they were hauling. Aboard the I-22, the skipper, Commander Kiyoi Ageta, declared to the assembled complement packed into the control room and the corridors leading away fore and aft: ‘Our ship is sailing for Hawaii now. Our objective is to discharge the special-type storage tube [a reference to the classified Type-A] to attack Pearl Harbor.’ The leader of the midget submarines once the flotilla had launched from the mother ships was Lieutenant Naoji Iwasa who was also based aboard the I-22.

Captain Sasaki’s plan of action for the five midget submarines constituting his Special Attack Force was simple. The midgets were to penetrate Pearl Harbor undetected and stay concealed inside the harbour until the main air assault began. Several options were then open to the midget submarine skippers. Firstly, once the first Japanese aircraft appeared overhead, they could immediately begin attacks on American warships inside the harbour. Secondly, the midget submarine commanders could wait for the lull between the first and second Japanese aerial waves, and attack then, creating an offensive bridge between the first two aerial assaults. Thirdly, the midget submarines could continue to remain concealed throughout the duration of the carrier plane assaults, only to emerge from the depths with the coming of darkness, and as the Americans began cleaning up launch their attacks by travelling anti-clockwise around Ford Island. Regardless of which plan the submarine skippers activated, their aim was to expend their torpedoes and then depart Pearl Harbor and make for the rendezvous point with the mother submarines at Lanai Island and recovery. Of course, these plans hinged on any of the five Type-As actually penetrating the entrance to Pearl Harbor undetected.

The weapons, which the First Flotilla was to launch against Pearl Harbor hours before the arrival of the main aerial attack force, were intriguing creations reflecting Japanese ingenuity and the advance of naval warfare. The vessels were not small, each Type-A midget submarine measuring 78.5 feet in length and weighing forty-six tons. A two-man crew consisted of a junior officer who commanded the boat and an enlisted man who acted primarily as helmsman. The Type-A could managed 19 knots submerged, and had a potential maximum range of 100 miles if running on the surface at a conservative 2 knots. The midget would approach its target surfaced until diving for the final attack run. The role of the junior officer midget commander was to give helm orders and operate the submarine’s periscope. The commander decided the submarine’s course, speed and depth, and, of course, targets, and transmitted these orders to the petty officer helmsman. The petty officer was charged primarily with control of the helm, and he was required to keep his hands on the wheel for the duration of the mission as the midget was extremely sensitive and the helmsman could easily lose control of the vessel. The petty officer was also required to dive and surface the boat by pulling and turning an assortment of valves that operated the midget’s ballast tanks. Finally, when given the order by the commander, he was charged with firing the two 17 feet long 18-inch torpedoes loaded in the midgets two ‘under and over’ tubes in the bow. Each torpedo was packed with 300 pounds of TNT. The single greatest challenge faced by the midget crews, apart from heat exhaustion and being unable to stand up inside the vessel for hours on end, was maintaining the submarine’s balance, the Type-A being renowned for its instability at sea.

The ‘mother’ submarines that would transport the midgets to the waters around Hawaii were all of the Type-C1-class. Five of these vessels were completed in 1940 and 1941 respectively, and they were dedicated midget submarine transports. As well as the Pearl Harbor operation, the Type-C1 submarines I-16 and I-20 launched their midgets outside of the Royal Navy’s base at Diego Suarez in Madagascar on the night of 30 May 1942. Although neither the crews or the midget submarines themselves returned to the ‘mother’ ships they did manage to damage the old British battleship HMS Ramillies, and to sink the tanker British Loyalty inside the anchorage. The very next night, 31 May, thousands of miles to the east, the I-22 and I-24 (along with other Japanese submarines) launched their midgets in an attempt to penetrate Sydney harbour in Australia.

In November 1942 the I-16, I-20 and I-24 all launched midgets off Guadalcanal, but the damage inflicted to a single American transport was a heavy price to pay for the loss of all of the Type-A midgets that participated in the operation.

When fully loaded the 358.5 feet long Type-C1 submarine weighed in at 3,561 tons, and was powered by twin diesel engines generating 12,400 horsepower. This meant that the submarine could reach 23.5 knots on the surface, and an equally impressive 8 knots when running submerged on 2,000 horsepower electric motors. At a fuel-conserving 16 knots a surfaced Type C1 could sail 14,000 nautical miles without refuelling. However, the boats’ trim characteristics were shot to pieces by each having a forty-six ton midget submarine armed with two torpedoes secured to their decks. The submarines travelled submerged by day to avoid aerial detection, coming to the surface at night to charge their batteries. Heavy winter seas constantly washed over the submarines’ decks as the maintenance crews charged with taking care of the midgets clambered and skidded about. The crewmen had to tie themselves to the submarines with lifelines, and many were washed overboard by the waves, only to climb back onto the decks bruised, exhausted and coughing up seawater. Onboard the I-24 one of the midget’s torpedoes was damaged when the mother ship submerged, and it took the crew a full night in foul weather to fit a new torpedo, manhandling the steel fish up from inside the cluttered and cramped interior of the I-24 and into the midget.

Unlike the Type-B1 submarine utilized by the Japanese in patrolling the American west coast in 1941–42, the Type-C1 was not fitted with a reconnaissance aircraft. Armed with a total of twenty torpedoes, eight torpedo tubes were arranged in the bow, served via two separate torpedo rooms located one above the other. The type also mounted a 140mm (5.5-inch) deck-gun, and a rather inadequate single .50 cal. machine gun for anti-aircraft defence. One hundred and one men were required to crew each Type-Cl submarine, a huge complement for a submarine of the era and once again not matched or surpassed until the nuclear age.

As the I-22 crept closer to Oahu, Sasaki watched the coastline intently, but little stirred ashore in the darkness. A few lights were visible and an occasional searchlight beam punched out into the night sky. Sasaki’s confidence soared, and he began to believe that the boys of the Special Attack Force really would be successful and prove the value of their training and their innovative new equipment. As the five midget submarines and the ten hand-picked officers and seamen prepared to strike at the mighty American fleet resting at anchor, Sasaki had ‘…a feeling of confidence and a renewed hope that the attack would be successful’. The I-24’s midget developed a further problem, this time a malfunctioning gyro-compass, a vital piece of equipment without which navigation would have been almost impossible. Ensign Kazuo Sakamaki, the midget’s commander, and Petty Officer Second Class Kiyoshi Inagaki, the crewman, worked feverishly to correct the problem and insisted that their mission should go ahead even if the compass was not fixed in time, demonstrating both their eagerness to complete a mission they had spent months training for, and a willingness to disregard their own lives in the process. Commander Hiroshi Hanabusa, skipper of the I-24, reluctantly agreed to this request, not overly keen to send men on one-way missions, because as an experienced seaman he knew full well that the chances of Sakamaki and Inagaki returning from the mission would be remote with such faulty equipment to contend with.

As the sun slowly set on Saturday, 6 December 1941, the five Japanese mother submarines had assumed their midget launch positions approximately eight miles south of the entrance to Pearl Harbor. The radio operators aboard were periodically picking up Hawaiian music from the shore that echoed eerily through the boats as men moved about making last minute adjustments to their equipment, and officers peered intently through periscopes at the darkened land before them. Slightly after midnight the I-16 began the launch of Sub-Lieutenant Masaharu Yokoyama, aged twenty-two, and his midget. After the launch the I-16 was to proceed to the second, and some would have argued even then, rather unrealistic stage, of the flotilla battle plan: to await the return of the midgets from their attacks on Pearl Harbor. The five big submarines would position themselves seven miles west of Lanai Island, which itself is eighty miles east of Pearl Harbor. There the plan called for them to wait for two days before departing the area. When (if) the midget submarines managed to locate a mother submarine at this location, the midget’s crew was to be recovered and the Type-A then scuttled. Because the mother submarines would fan out off Lanai Island, more than one midget might rendezvous with the same submarine, so it was decided that recovery of the Type-As was impractical. The exhausted but hopefully victorious crews would have priority, as the equipment could be replaced. All of this was rather academic, as many officers and men aboard both the mother submarines and midgets knew, for the midget crews had already made their peace with God, and were prepared to sell their lives for the sake of the Emperor.

Yokoyama and his crewman, Petty Officer Second Class Sadamu Ueda, had already made their preparations for what they believed to be their final voyage. Should they be killed they would become ‘War Gods’, venerated at the Yasakuni Shrine in Tokyo. They could take satisfaction that if they died the Emperor himself would visit the shrine each year to pay his respects and pray for their souls. Religious rites had been conducted aboard the submarine, prayers said, and final farewell letters penned to their families back in Japan, the men enclosing locks of hair and fingernail clippings so that their families would have something physical to cremate should they perish. Both men had dressed in clean uniforms, as Shinto rites dictated, and with souls and bodies purified they had clambered up into their midget submarine from inside the I-16. The telephone link between the midget and the mother submarine was disconnected and at 12.42 a.m. on Sunday, 7 December, the midget lifted off under the water and departed for war.

Aboard the command submarine I-22 Lieutenant Iwasa, leader of the midget submarine group once they had left the mother ships, and his crewmen, Petty Officer First Class Naokichi Sasaki, clambered aboard their vessel. Both men carried family swords strapped to their backs in white cloth sashes. Just before Iwasa disappeared up the ladder into the Type-A he briefly addressed the crew of the I-22. He was full of gratitude for their assistance in getting him and Sasaki to the target area: ‘Our work begins now. Believing in divine help, we are about to depart to do our utmost to fulfil our final task so as not to betray your trust and expectation in us,’ he said, adding, ‘I pray for the future successful battles of I-22. Farewell.’ Iwasa bowed to the crew, who returned his salute, and then was sealed inside the midget. Grasping the inter-submarine telephone, Sasaki spoke to Iwasa for the final time before the midget departed. ‘Congratulations in advance on your success’, he said, ‘I hope you will do your job well. Good luck!’ Iwasa thanked his commanding officer for bringing all of them this far, and his final words indicated his acceptance of the nature of the coming mission when he said, ‘I wish you [Sasaki] to look after my private affairs.’ With the final farewells said the midget was released into the open sea at 1.15 a.m. The I-22’s crew faced the direction the midget had sailed and saluted in silence. It was now a waiting game, waiting for news of a series of successful attacks made by the men they had come to know during the journey across the Pacific, and a period of waiting for their triumphant return, however remote that possibility appeared.

A similar scene to that being played out aboard the I-22 had just concluded aboard the I-18, as Sub-Lieutenant Shigemi Furuno and Petty Officer First Class Shigenori Yokoyama lifted off and motored towards Pearl Harbor. Next to depart was Ensign Akira Hiro-o and Petty Officer Second Class Yoshio Katayama from the I-20. Aboard the I-24, the midget’s defective gyro-compass was still not functioning properly, so Sakamaki determined to navigate towards Pearl Harbor at periscope depth instead, navigating by eye. It was a suicidal decision, but both men were determined not to be left behind kicking their heels while their comrades made history. They were the last midget to depart, and lifted off at 3.33 a.m. The loss of the gyro-compass was soon keenly felt by Sakamaki, as he vainly tried to hold the submarine on a course for the harbour by taking regular periscope readings, but the midget floundered about, taking a long time to edge towards his objective as the dawn fast approached. All of the midgets were supposed to penetrate the entrance to the harbour before daybreak, and be in position to time their attacks with those of the carrier task force aircraft. This became increasingly remote for Sakamaki and his submarine as the slow progress meant he would arrive at the entrance to Pearl Harbor after the other midgets, and the American base would be fully alert to a Japanese presence.

The first line of defence that the five Japanese midget submarines would encounter, and have to slip by unnoticed if they had a chance of penetrating the harbour, were three American minesweepers, the USS Crossbill, Condor and Reedbird. Their job was to patrol the harbour approaches, and a First World War-vintage destroyer located behind them supported them in this task. The USS Ward had been launched during the middle of 1918, though she had not seen any action during the earlier conflict. In fact, the Ward had never fired her guns in anger, and after the First World War the vessel had been mothballed and placed in reserve at San Diego until called up for service in early 1941. Commissioned back into service, and assigned to the US Pacific Fleet as a harbour defence and patrol vessel, she was placed under the command of thirty-five year old Lieutenant William Outerbridge. At 3.57 a.m. the Condor reported sighting what appeared to be a small submarine periscope about two miles outside of the harbour buoy, and the Ward motored over to assist in a thorough search. The Ward conducted a sonar search but turned up no contacts, and after ninety minutes gave up and returned to her original patrol sector.

The next line of defence designed to prevent unauthorized penetration of Pearl Harbor was an anti-submarine and boat net stretched across the harbour mouth. Sections of this net could be opened to permit the passage of vessels into and out of the harbour, and it was the job of the patrol vessels to monitor who was coming and going. Around 5 a.m. the patrol boats Condor and Crossbill headed into the harbour through a gate that was opened for them. The gate was left open as the USS Antares, a navy repair ship towing an empty steel barge, was expected to pass through shortly afterwards. Sub-Lieutenant Yokoyama, aboard the I-16’s midget, saw his chance and decided to follow the Antares through the gate, hopefully fooling the sentinels on watch. Lookouts aboard the Ward watched the Antares pass in front of their vessel as she made her way towards the gate. Something, however, caught their attention, for their appeared to be an object moving in the water between the repair ship and the barge. After some animated discussions aboard the Ward, it was concluded that the object was most probably a loose buoy. Pearl Harbor had received many submarine sightings over the past year, all of which had turned out to be false alarms, and no one was in the mood for jumping to conclusions just yet. The sun was up by now, and the officers and lookouts took up their binoculars and trained them on the object in the water for a closer look. The ‘buoy’ appeared to be travelling at about 5 knots, and no one knew of an inanimate navigational marker doing this before. Lieutenant Outerbridge faced a dilemma: perhaps the object was some kind of new secret weapon being developed by the US Navy, and if he fired on it the consequences for him could have been dire. However, he had not been informed by 14th Naval District to expect any such activity in his sector, and the object was, after all, inside the restricted zone. Having made up his mind to attack the object, Outerbridge ordered the guns manned and the men to battle stations. By now seamen aboard both the Ward and the Antares were reporting that the object looked much less like a buoy, and much more like a small submarine conning tower cutting the surface of the water like a shark’s dorsal fin. A Catalina flying boat circling overhead had also taken an interest in the object, and dropped some smoke bombs to mark its position for the warships.

Steel Coffins: 7 December 1941 Part II

USS Ward opens fire on a Japanese sub. Art by Tom Freeman.

At 6.45 a.m. the Ward opened fire, the first shot from its No. 1 gun sailing over the little conning tower to land in the sea beyond. At this point the midget submarine was seen to noticeably increase speed, the commander evidently attempting to charge the open gate in the net and get inside the harbour. Shot number two from the Ward decided the issue, however, as the round ploughed into the base of the conning tower, but did not explode. The midget immediately heeled over violently and started to sink. Outerbridge decided to make sure and passed alongside the foundering submarine, four depth charges rolling off the back of the destroyer. The detonations finished the Japanese submarine, and she disappeared rapidly into the disturbed sea. The Ward now signalled to shore a message for the attention of Rear-Admiral Claude C. Bloch, Commandant of the 14th Naval District, and responsible for the Pearl Harbor base and facilities: ‘We have dropped depth charges upon sub operating in defensive area.’ Theoretically, such a message should have set alarm bells ringing all over Pearl Harbor that something was amiss, but when the first message was received (a second followed a couple of minutes later) at the Harbor Control Post at 6.51 a.m., getting the signals sent up the chain of command quickly proved difficult. A twenty-minute delayed ensued while the messages were decoded and re-sent, and because it was very early on Sunday morning only skeleton crews were manning the communication equipment anyway. The duty officer in charge of the security of the antisubmarine and ship net guarding the harbour, Lieutenant Harold Kaminski, took it upon himself to try to get things moving regarding some sort of response to the Ward’s messages. He telephoned Admiral Bloch’s chief-of-staff, Captain John B. Earle, and Kaminski also ordered the ready-duty destroyer, the USS Monaghan, to ‘proceed immediately and contact the Ward in defensive in sea area’. Captain Earle in turn telephoned Admiral Bloch, and the two senior officers discussed the reports, and concluded that it was probably just another false submarine sighting. With the Monaghan assisting the Ward the two vessels were more than capable of dealing with the situation. Earle told Kaminski to inform the 6th Fleet’s Operations Officer of the event, but to take no further action. Confusion reigned ashore, as the Ward now reported that she had intercepted a fishing sampan inside the security defence zone, and required a navy cutter to escort the vessel away from the vicinity. When Earle was informed he wondered why the Ward would go off intercepting sampans when she believed a submarine to be in the area, and concluded that the Ward’s crew had misidentified their earlier submarine contact. Therefore, it was just another false alarm.

The Japanese air armada of carrier aircraft, led by Commander Mitsuo Fuchida, was fast approaching Oahu. Another American destroyer, the USS Chew, reported to 14th Naval District that she had attacked and sunk a midget submarine outside the entrance to the harbour. The Ward continued depth-charging operations as American patrol vessels charged about seeing submarines everywhere. They were still busily engaged in this when the first Japanese aircraft passed overhead and roared down to bomb and strafe Ford Island, Battleship Row and Hickam Field US Army Air Corps base. The reports of submarine contacts were soon drowned out by the full-scale aerial assault being made on the naval base and vessels moored in the harbour. The Ward and the Monaghan sounded ‘General Quarters’ at 8 a.m., after a Japanese bomb landed close to the Monaghan. Anti-aircraft guns were hastily manned, the crews doing what they could to return fire against the Japanese planes knocking Pearl Harbor and the Pacific Fleet to pieces virtually at will.

By 8.14 a.m. the harbour patrol destroyers had commenced a steady anti-aircraft barrage directed against Commander Fuchida’s carrier air group. The Monaghan was ordered to move down the harbour approach channel, and while making this journey she encountered the seaplane tender USS Curtiss at 8.53 a.m. Although a massive air battle raged overhead, the Curtiss was flying signal flags indicating that a submarine was threatening her. Crewmen aboard the destroyer watched as the Curtiss trained her guns on the water and opened fire at a floating object. The destroyer quickly identified the object as a small submarine before the craft slinked beneath the surface, reappearing at 8.40 a.m. This midget submarine was well within the harbour defences, cruising around off Ford Island in the centre of the harbour. The midget had been able to penetrate so deeply into Pearl Harbor because, as related earlier, a gate had been left open from 5 a.m. that morning at the entrance to allow the USS Antares to enter. It had remained open while the destroyer USS Ward had attacked and sunk a midget submarine by the harbour entrance, and no one had subsequently closed the boom and net as Pearl Harbor came under sustained and heavy air attack that morning. The midget that was lurking off Ford Island shot a single torpedo that sailed past the Curtiss, narrowly missing the light cruiser USS Rayleigh, before running into the land opposite Pearl City and exploding.

The Monaghan now attempted to deal with the midget, firing a single 5-inch shell at the small conning tower from her main gun, but the midget turned about and shot its final torpedo at the destroyer. The Japanese torpedo shot past the Monaghan and blew up when it struck land at Ford Island. Lieutenant-Commander W. P. Burford, captain of the Monaghan, decided upon a drastic course of action at this point. He ordered the engine room to give him full speed, and then pointed the destroyer’s bows at the little submarine and set to ram it. After a few seconds the destroyer struck the midget, which was dragged along the length of the Monaghan before it passed by. A quick-thinking torpedoman stationed in the destroyer’s stern watched the midget submarine trail along the side of his ship, and quickly fused a depth charge that he dropped overboard alongside the midget. Burford ordered another depth charge dropped, but then the Monaghan ran aground onto a submerged mud bank. The two depth charges exploded, and great geysers of seawater, black with oil, shot high into the air marking the destruction of the Japanese submarine. The Monaghan extricated herself from the mud. All the time this little action was occurring Japanese air attacks continued all around the Americans, but the Monaghan and her crew were unharmed.

The Japanese submariners continued in their efforts to press home attacks on the US fleet. At 9.50 a.m. the destroyer USS Blue obtained a contact with a suspected submarine outside the harbour. The Blue laid a pattern of depth charges and reported the probable destruction of the enemy vessel. Attempting to exit the carnage that was Pearl Harbor that morning, the light cruiser USS St. Louis dodged two torpedoes running towards her before they exploded. A small submarine conning tower was seen, and the cruiser engaged the target with her main batteries, claiming to have scored hits.

The I-24’s temperamental Type-A, whose defective gyrocompass had almost cost Ensign Sakamaki his place on the mission, was now the only midget still operational. Sakamaki’s boat, however, had been extensively damaged by the depth charge barrages laid at the harbour entrance. The midget’s steering gear was almost gone, and the batteries were cracked and leeching noxious fumes into the crew compartment as Sakamaki and Petty Officer Inagaki struggled to nurse their vessel towards the harbour entrance channel, and its open gate. Both men were buoyed up immensely when Sakamaki viewed through the periscope the huge columns of black smoke rising from Pearl Harbor, indicating the success of the aerial assault. Sakamaki was determined that he would add to the destruction with his two torpedoes, never considering abandoning his mission and attempting to rendezvous with the mother submarines. At 8.15 a.m. Sakamaki surfaced the boat to attempt to locate the harbour entrance and a potential target through his periscope, only to have the American destroyer USS Helm loom large in the lens as the ship raced for the open sea. The destroyer clearly discerned the midget submarine limping towards the harbour entrance. As the two vessels converged, the Japanese submarine ground onto a submerged reef, exposing herself completely to the Helm’s guns. But, although the destroyer blazed away no hits were made, and gingerly, Sakamaki was able to get the Type-A off the reef and submerged. Once beneath the waves the two Japanese sailors assessed their situation. The air inside the submarine was becoming unbearable, and the men were in danger of being overcome by the battery fumes. The defective steering meant the Type-A wallowed around uncontrollably, making directed movement or assuming a firing position almost impossible. One of the torpedo tubes had also become inoperable as a result of striking the reef, so Sakamaki decided to use his entire vessel as one giant torpedo and ram the next American warship they encountered. This would result in their deaths, but both men were fully committed to such an end. For the rest of the morning Sakamaki vainly tried to obtain some measure of control over the submarine, but another grounding on a reef knocked out the second torpedo tube. The midget was now adrift, with the crew swimming in and out of consciousness in the thick air inside the submarine, as they attempted to reach Lanai Island and the mother ships waiting there. Sakamaki opened the submarines hatch to air the crew compartment, before falling asleep again, and for the rest of the night of the 7–8 December the submarine drifted about, hatch open, crew asleep until further efforts were made to use the engine to get them to Lanai. The engine barely worked, and the attempt was abandoned, for without a compass they also had no idea where they were, and which direction salvation lay. At some point on the early morning of 8 December the midget submarine ran aground for the final time on a reef some way off a deserted beach. Sakamaki ordered the vessel abandoned, and the two Japanese plunged into the heavy sea and attempted to swim for the shore. Unfortunately, Petty Officer Inagaki was lost in the waves and drowned, while Sakamaki washed up exhausted but alive on Waimanalo Beach, close to a devastated Bellow’s Field Army Air Corps base. Sakamaki came ashore virtually into the arms of a patrol of American soldiers from the 298th Infantry Regiment and was taken prisoner. Sakamaki was the first Japanese serviceman taken prisoner during the Second World War, and the young naval officer was stricken with humiliation and shame. It was to prove an intelligence coup for the Americans, and they hoped to discover from Sakamaki more about the strange little submarines that had so boldly attacked the anchorage.

The First Special Attack Flotilla’s assault on Pearl Harbor was an abject failure. All of the Type-As were destroyed during the operation, and not a single torpedo fired by the midgets struck a single American ship. Of the ten sailors who crewed the vessels, only Ensign Sakamaki survived the ordeal. However, the men who undertook the mission had not really thought much of their chances of coming back alive. The Imperial Japanese Navy honoured the memories of the nine dead men, and they were elevated to the level of war-gods, and posthumously promoted. Lieutenant Iwasa, the leader of the First Special Attack Flotilla was promoted to commander. Yokoyama and Furuno were advanced to lieutenant-commanders, and Ensign Hiro-o was made a lieutenant. Petty Officer First Class Yokoyama and Sasaki were commissioned with the rank of special ensign, while Petty Officer Second Class Ueda, Katayama and Inagaki became warrant officers in the afterlife. Ensign Sakamaki, who had had the misfortune to fall alive into enemy hands, was studiously ignored in the praise and honours distributed after the operation. His bravery was, in the eyes of the Imperial Navy, cancelled out by his failure to sacrifice his life for the Emperor when placed in an impossible situation. To add insult to injury, the scuttling charge that Sakamaki had set inside his midget before abandoning ship had failed to detonate, and the Americans were able to recover an intact example of the Type-A to study.

As regards American preparedness concerning this new form of underwater warfare, the harbour defences were not impregnable to submarine attack even when carefully monitored. Although the Americans usefully would leave the gate in the harbour protective net wide open between 4.58 and 8.46 a.m., even if the gate had been firmly shut it would not have been impossible for the Japanese midget submarines to have penetrated Pearl Harbor. They could have passed beneath the net. According to Gordon W. Prange on 7 December 1941, the net extended to a depth of forty-five feet, but the harbour channel plunged down to a maximum depth of seventy-two feet. The Type-A midget was twenty feet tall, from the bottom of the keel to the top of the conning tower, and this would have given a midget seven feet of leeway beneath the net. Because the Americans left the net gate open for so long none of the five Japanese midgets was forced to attempt the tricky manoeuvre of passing under the net, but it remain theoretically possible, further demonstrating the usefulness of the Type-A in overcoming harbour defence measures.

The activities of the other submarines involved in the Pearl Harbor operation were similarly disappointing. The four boats of the 3rd Submarine Squadron achieved only two kills before returning to Kwajalein on 17 December. The I-68 was damaged after being heavily depth-charged by American patrol boats thirty miles from the entrance to Pearl Harbor on 7 December, and the I-69 ended up entangled in floating line off southern Oahu after an unsuccessful torpedo attack on a merchant ship. Whilst caught up the boat was also depth-charged, and the crew only managed to extricate their submarine by working flat out for forty hours. The boat came to the surface with the crew almost asphyxiated by the stale air onboard. The I-72 managed to sink a small freighter 250 miles south of Oahu on 8 December, and the I-75 made a similar claim when 100 miles south of Kauai on the 17th. The seven submarines forming the 1st Submarine Squadron under Rear-Admiral Sato only managed to sink one merchant ship on 11 December. The seven ocean cruising boats of 2nd Submarine Squadron would continue patrols until 11 January 1942. The I-7 successfully conducted a dawn reconnaissance of battered Pearl Harbor on 17 December, the E14Y1 floatplane obtaining enough data to enable a complete damage report to be sent to Tokyo. Three days previously the I-4 had sunk the 4,858-ton Norwegian merchant ship Hoegh Merchant off Makapuu Point, Oahu.

Later, the Japanese had endeavoured to find and destroy the American aircraft carriers that they had missed during the Pearl Harbor attack, and in January 1942 a Japanese submarine had torpedoed the USS Saratoga 500 miles west of Hawaii. The Saratoga, though damaged, survived to fight again, and on every occasion Japanese Naval Intelligence discovered the possible locations of American aircraft carriers all forces were directed towards locating and sinking them, often to the detriment of submarine operations then in play. This kind of strategy continued to demonstrate that in the Japanese Navy’s mind submarines were vessels designed to work in close cooperation with the surface fleet, taking them away from the more valuable, with hindsight, tasks of sinking Allied merchant ships. The Japanese resolutely refused to use their submarine force in a similar fashion to the Germans, often with terrible results for the submarines employed against the increasingly technologically advanced antisubmarine detection equipped Allied warships.

The Japanese determined to understand why their massively potent submarine service deployed during and after the Pearl Harbor operation had failed to achieve the kind of impact expected. One reason was a command structure that saw the commander of 6th Fleet submarines, Admiral Shimizu, ensconced firmly on dry land at his headquarters in Kwajalein. Shimizu was simply too far removed from the situation to make much impact, or to have changed plans while the operation was ongoing. The overall commander also had a penchant for sending radio messages to his submarines when they were laying in position around Hawaii before the attack, alerting the Americans to a suspicious build-up of Japanese forces in the region. The Americans took care in routing merchant ships away from the reported locations of Japanese submarines, thereby limiting the boats’ abilities to find and sink targets around the islands when war came. Planning was rather uncoordinated, with much of the potential the submarines posed being squandered, leading to all the glory going to the Imperial Naval Air Service. A final factor that upset the Japanese sub-surface plan was the unexpected strength of American anti-submarine forces, emphasized by the fate of the Special Attack Force midget submarines.

Target California I

Japanese 6th Fleet Headquarters at Kwajalein had come up with a further innovative use for submarines that had already been employed in the attack on Pearl Harbor. The seven submarines of 1st Submarine Squadron were given a new task, and were to bring the war in the Pacific to America’s doorstep. Joined by the I-10 and I-26 from the original Pearl Harbor Reconnaissance Unit, Vice-Admiral Shimizu ordered the nine submarines to pursue the enemy eastwards and to patrol off the American west coast. The American public and military were already jittery following the audacious Japanese aerial and submarine attack on Hawaii, and rumours abounded of the likely next move by the Japanese towards the mainland of the United States. Perhaps an enemy landing on the lightly defended Pacific coasts of California or Oregon was a distinct possibility? The Japanese knew of American invasion fears and the redeployment of Japanese submarines close to these very coasts would hopefully have an adverse effect on civilian morale far outweighing any strategic or military impact they would have been able to make with the limited resources placed at their disposal.

Each of the eventual eight Japanese submarines that moved into position was ordered to interdict American coastal shipping by lying off the major shipping lanes, such as those located off Los Angeles and San Francisco. Rear-Admiral Sato, commander of 1st Submarine Squadron, was aboard his flagship, the I-9, directing operations at sea. It was expected that each skipper would make each of his seventeen torpedoes tell, and 6th Fleet had ordered them to only expend one torpedo per enemy ship. The submarine captains had also been ordered to expend all of the ammunition for their submarine’s 140mm deck-gun before returning to base. This would be achieved by supplementing the limited supply of torpedoes carried onboard by blasting merchant ships to pieces with the submarine’s artillery piece, and then turning the gun on vulnerable American coastal installations. It was a plan intended to spread fear and panic along the huge Pacific Ocean coast of the United States, a plan to set the inshore waters and shoreline ablaze.

The I-17 was a Type-B1 Japanese fleet submarine skippered by Lieutenant-Commander Kozo Nishino, an example of the most common and numerous class of submarine employed by Japan during the Second World War. Between 1940 and 1943 twenty were constructed, earlier examples such as the I-17 being equipped with the ingenious Yokosuka E14Y1 floatplane used for reconnaissance. A watertight hanger was fitted aft of the conning tower, the aircraft being launched by means of a catapult and ramp built into the submarine’s deck. Each B1 submarine was 356.5 feet long with a top speed on the surface of 23.5 knots, or 8 knots submerged and running on electric motors. Prior to the introduction of nuclear-powered submarines in the 1950s the vessels that fought in the Second World War were essentially submersibles rather than true submarines. Japanese, German, British and American submarines, and the submarines of every nation able to maintain undersea fleets, were all limited by their central power sources. Submarines at this stage were powered by diesel engines while they were at the surface, making them relatively fast and ideal platforms to launch anti-commerce and anti-warship attacks from, especially when cloaked by the cover of darkness. The power of large Japanese diesels fitted to many types of their submarines produced enough speed to allow the vessels to keep pace with the surface battle fleet – which remained a primary consideration of Japanese submarine designers throughout the Second World War. If forced below the surface of the water, or if attempting a submerged attack, the submarine was powered by electric motors running off cumbersome and space consuming batteries. The submarine immediately lost its speed and agility beneath the sea, and could only remain submerged while the air aboard remained breathable for the crew. The Japanese would not be able to match the Germans in advanced submarine design during the Second World War to overcome the twin problems of increasing underwater speed and staying semi-permanently submerged during patrols, and their submarine force would pay a heavy price as Allied anti-submarine technology developed exponentially as the war progressed. The Germans went some way to overcoming the problems of extended periods spent below the surface and running on electric motors by the incorporation of a Dutch design known as the snorkel. Basically, a submarine was fitted with a large mast that could be raised until the head was above the surface of the water, the submarine remaining submerged. Air would be sucked into the snorkel head, allowing the diesel engines to be run while the submarine was submerged, and the boat aired, theoretically enabling a German U-boat to conduct its patrol entirely submerged and therefore rendering it less vulnerable to Allied attacks. Fitted to most late-war German U-boats the snorkel often malfunctioned due to poor construction or components, and if waves splashed over the snorkel head the diesel engines would suck air from inside the U-boat, causing the crew great discomfort, especially to their ears and occasionally causing unconsciousness. Allied warships could also locate the snorkel head in the same way as a periscope mast, and the submarine would be attacked. Japanese submarines were not fitted with this technology, even though the Germans gave the Japanese detailed plans of the apparatus as part of ongoing German-Japanese trade and military technology exchanges between 1942 and 1945.

If a Type-B1 submarine was run at full speed on the surface the skipper would have rapidly used up his available diesel fuel, severely curtailing the boats operational potential, so a top speed was simply the boats potential power. Rather, a sensible skipper would be able to take his B1 on a round-trip patrol of approximately 14,000 nautical miles at a conservative 16 knots without requiring a single refuelling pit stop. This would make the B1 submarine the ideal platform with which to sail across the Northern Pacific to the west coast of the United States, and bring the war to America’s doorstep. Added to the potency of the B1’s great range was a 140mm deck-gun designed to assist a skipper in sinking ships. The deck-gun fired armour piercing anti-ship ammunition, designed to penetrate the steel hulls of ships and explode within. Pump a sufficient quantity of these cheap shells into a merchant ship and the result was a foregone conclusion, and just as effective as a torpedo. It was a more economical option than expending one of the seventeen torpedoes carried aboard the B1 through one of the boat’s six torpedo tubes. Ninety-four officers and men crewed the B1, including two pilots and two observers to man the Yokosuka floatplane (one pilot and observer acting as a reserve crew).

Although the B1 was not the biggest submarine type employed by the Imperial Navy, the Japanese nonetheless cornered the market in producing large submarines during the Second World War. The B1 was bigger, better armed, quicker and with a greater range than the closest comparable German U-boat type. For example, the Type IXC U-boat had given the Germans the ability to take the war to the east coasts of the United States, Canada and all around South Africa by 1942 and could motor an impressive 11,000 nautical miles at 12 knots before requiring refuelling. However, the Type IXC, at 252 feet long, was nearly 100 feet shorter than the Japanese B1, and was armed with fourteen torpedoes and a 105mm deck-gun and anti-aircraft weapons. Importantly, although German U-boats were smaller, had a shorter range and carried less munitions than their Japanese counterparts, they were quicker to submerge and were progressively equipped with superior technology such as radar detectors and snorkels that increased their survivability. The fundamental difference between a Japanese submarine and a German U-boat was not so much the technical specifications and technologies utilized in creating them, but the method in which they were employed. The Japanese viewed submarines as essentially fleet reconnaissance vessels to replace cruisers in that role, whereas the Germans saw submarines as the tool with which to sink millions of tons of enemy merchant shipping in order to reduce the industrial/military output of their opponents, and create hardship on the enemy home front.

Nishino aboard the I-17 was proceeding on the surface in the pre-dawn darkness fifteen miles off Cape Mendocino, California on 18 December 1941, lookouts armed with powerful binoculars patiently scanning the barely discernable horizon on all points of the compass, and studying the sky in case of air attack. They were quiet, speaking only briefly in hushed tones, using their ears as well as their eyes to search out engine noises above the rhythmic reverberations of the I-17’s twin diesels as they lazily pushed them through the dark Pacific waters. The eerie red glow of low night lighting crept up the conning tower ladder from the control room below, etching the faces of the Japanese submariners into fixed masks of concentration and anticipation. Suddenly, as the first glow of dawn began to rise on the eastern horizon a lookout let out a guttural exclamation. His arm shot out in the direction of the approaching ship, a compass bearing relayed to the helmsman below, as Nishino ordered his vessel closed up and made ready for action. In normal circumstances a submarine captain would attack his intended target with a spread of torpedoes, a staggered shot that would fan out to intercept the intended target(s) after calculations of the speed and direction of the prey had been computed into the attack plot. Nishino was under strict orders to only expend a single torpedo per enemy ship, which did not give him much latitude for attack, and meant that the Japanese submarine would have to move up very close to the target ship to be sure of not wasting the valuable mechanical fish. Nishino decided that the best method of attack as the merchant ship hove into view was the employment of the deck-gun for the time being. If he could inflict sufficient damage to the freighter with his gun, enough to stop her, he could then decide whether to finish her off with more armour-piercing shells or close in for a single torpedo strike against a static target. The I-17, however, was rolling heavily in the swell as crewmen busily prepared the deck-gun for immediate action, manhandling shells from the gun’s ready locker, ramming home a round with a solid thump as the breech was closed and the gun commander awaited the signal from the bridge to open fire.

The ship in the gunners’ sights was the American freighter Samoa under the command of Captain Nels Sinnes, who was about to be abruptly awoken by the report of a submarine close by. The Samoa had already sustained damage, but not from enemy action. She had been caught by a heavy storm which had washed away one of the ship’s lifeboats. The Samoa also had a noticeable list to port, as the engineers had been shifting water in the ballast tanks following the battering from the ocean. The pronounced list, and the remnants of the wooden lifeboat hanging from its launching davits, would be providential in saving the ship from the attentions of the I-17 in the minutes that followed.

Captain Sinnes quickly dressed and, grasping a life jacket, ordered his crew to muster at their lifeboat stations. The sailors frantically stripped the covers from the open boats and began swinging them out on their davits ready to launch when the Japanese opened fire. Five times the I-17’s deck-gun barked, its flat high velocity report sounding out across the empty sea, the armour-piercing shells tearing towards the defenceless Samoa. Four missed to fountain in the choppy ocean, the Japanese gunners pitching hot, steaming shell cases overboard as others fetched fresh shells from the ready locker. The fifth shell exploded above the Samoa with an ear-splitting crack, white-hot shrapnel pummelling the deck. The Japanese submarine was rolling erratically on the disturbed sea, making it difficult for the gunners to accurately target the American ship, and they were reduced to flinging shells in the general direction of the enemy vessel and hoping for a lucky strike. Commander Nishino quickly tired of this pointless shooting and ordered a surfaced torpedo attack, the fish leaving the I-17’s bow with a hiss of compressed air and a trail of bubbles, quickly crossing the barely seventy yards that separated hunter and prey. In the early dawn light it appeared to the crews of both vessels to be a foregone conclusion.

Incredibly, as the crew of the Samoa braced for impact and a thunderous explosion, nothing happened. The torpedo passed clean underneath the merchant ship. The blind torpedo cruised on a short distance and then erupted in a massive tumult of water, smoke, fire and flying shrapnel. Fragments of the torpedo thumped harmlessly onto the Samoa’s deck, the I-17 a low black shape that drifted ominously closer to the American ship. Officers aboard the submarine attempted to assess the damage the torpedo, which they erroneously assumed had struck the Samoa, had caused. Now perhaps no more than forty feet from the side of the merchant ship, the early morning gloom frustrated their efforts. Still the I-17 closed with the Samoa, coming to within fifteen feet of the hull. Someone aboard the I-17, according to the Americans, yelled out in English ‘Hi ya!’ Captain Sinnes yelling back ‘What do you want of us?’ when he already knew the answer. From his position alongside the Samoa Nishino observed the vessel’s heavy port list and assumed she was doomed. The I-17 slowly pulled away and disappeared. Nishino instructed his radio operator to report a successful kill to the I-15, coordinating submarine operations from her position off San Francisco.

The Samoa arrived safely in San Diego on 20 December after her close encounter, saved by storm damage and the poor early dawn light. On the same day Nishino redirected his submarine to its original position off Cape Mendocino, some twenty miles from the American coast. The crew of the I-17 awaited another target of opportunity, buoyed up by their apparent first successful sinking of an enemy vessel of the mission. The day wore on with no sightings of American merchant ships, until, bathed by early afternoon winter sunshine, the lookouts were once more laboriously scanning the horizon and biding their time. Nishino made no attempt to disguise his presence so close to the coast, believing he had little to fear from American naval or air forces still reeling from the devastating attack on Pearl Harbor fourteen days previously. Just after 1.30 p.m. the sight of the oil tanker Emidio heading towards San Francisco rewarded Nishino’s patience. The Emidio was only carrying ballast, returning empty from Seattle’s Socony-Vacuum Oil Company facility.

Captain Clark Farrow reacted as swiftly as he could to the report of a submarine gaining on his ship. Nishino aboard the I-17 ordered full power, the big diesels churning confidently ahead, the submarine making fully 20 knots, her exhausts trailing blue clouds of fumes into the clear Pacific air. Captain Farrow lightened his ship, dumping ballast that made the Emidio steady in the water but painfully slow, frantically ringing ‘full speed ahead’ on the engine room telegraph. The I-17 cut through the water, closing rapidly on the Emidio’s stern, crew racing to man the deck-gun as Nishino manoeuvred his boat for the attack. It was imperative that the American ship be prevented from radioing for assistance, and therefore reporting Nishino’s position to United States forces. Captain Farrow was already a step ahead of Nishino, however, as he had ordered his radio operator to send the following short Morse message: ‘SOS, SOS: Under attack by enemy sub.’

Nishino ordered the gun crew into action, the first shell exploding close to the Emidio’s radio antenna, blowing the fragile communication mast into useless scrap. In rapid succession the submarine’s gun banged twice more, the shells screaming across the ocean into the defenceless Emidio, a lifeboat exploding into smouldering matchwood. Ashore, the US Army Air Corps were already scrambling a pair of medium bombers following the receipt of the Emidio’s distress signal and position, in the hope of destroying the Japanese submarine. Captain Farrow realized his ship was doomed, as the bombers would take some time to arrive, and he ordered the engines stopped. Meanwhile, the plucky radio operator had managed to restore communications with the shore by erecting a makeshift antenna. A white flag was hastily run up a mast and the tanker gradually slowed. The crew worked feverishly to swing out the remaining lifeboats while under constant shellfire from the I-17, Nishino ignoring the white flag and refusing to give the merchant seamen time to depart in the boats. It was not long before another shell found its mark, blowing three unfortunate crewmen into the water as it ploughed into their lifeboat. Twenty-nine crewmen were crowded aboard the lifeboats and pulled hard on the oars in an attempt to get clear of the Emidio, while four men, including the resourceful radio operator, remained aboard the ship, perhaps from a refusal to give up the vessel, or out of ignorance of the order to abandon ship issued by the captain.

On board the I-17 lookouts had reported two black dots approaching from the mainland, which could only mean aircraft. Nishino ordered the bridge cleared, the submariners hastily clattering down into the pressure hull, securing the hatches as the submarine blew its tanks and slid beneath the waves in a swirl of white water. The Emidio’s remaining crewmen now turned their eyes skyward as the American bombers roared in low over the stricken merchantman. The two aircraft circled the spot where the I-17 had a moment before submerged, eventually releasing a single depth charge. The I-17 lurched violently as the depth charge detonated, but it was not close enough to cause the submarine any damage. Perhaps realizing that the American aircraft lacked the wherewithal and experience to launch a more devastating and coordinated anti-submarine attack Nishino did the opposite of most submarine skippers in his position. Ordering the I-17 to periscope depth Nishino swiftly relocated the fully stopped Emidio. Orders were issued to partially surface the boat, and a torpedo was launched at the stationary American ship 200 yards distant. The torpedo ran true, impacting in the Emidio’s stern and detonating inside the ship with a massive blast of fire, smoke and debris. The Emidio lurched over as the engine room rapidly filled with freezing seawater. The torpedo claimed two of the four crewmen who had not vacated the ship earlier, and a third was injured. The radio operator, topside in his shack, frantically transmitted ‘Torpedoed in the stern’ before throwing himself clear of the ship into the sea. The surviving engineer, though wounded, also managed to struggle clear of the Emidio, and along with the radio operator he was plucked to safety by the small flotilla of lifeboats standing off the tanker.

The I-17 slipped once more beneath the waves as the two American bombers roared in to resume their ineffectual attack. Another depth charge plummeted into the sea and detonated in a giant plume of white water, concentric circles created by the sonic force of the explosion pushing out from the epicentre. The I-17 escaped damage once more and motored quietly away from the scene, sure again of a confirmed kill.

The Emidio, though grievously wounded and abandoned by her crew, drifted off with the current. Lost for several days from human eyes, this Second World War Mary Celeste eventually ground up against jagged rocks opposite Crescent City, California, over eighty miles from her encounter with the I-17. As for her crew, their ordeal was to be sixteen hours in open boats and battling through an unsettling rainstorm before rescue by the US Coast Guard lightship Shawnee located off Humboldt Bay.

The I-23, another Type-B1 Japanese submarine with orders to sink unescorted American merchant ships, was active at the same time as the I-17 was attempting to sink the tanker Emidio. Constructed at the Yokosuka Navy Yard, the I-23 had entered service in September 1941. She was just in time to play a crucial part in ‘Operation Z’, the submarine contribution to the Japanese victory at Pearl Harbor. On 13 December the I-23 began her relocation from the waters off Hawaii for the west coast of the United States.

On 20 December the I-23 was approximately twenty miles off Monterey Bay, California, and with a target in sight. The American tanker Agwiworld, a 6,771-tonner belonging to the Richmond Oil Company was the Japanese target. Like a fighter pilot swooping down on a hapless rookie opponent, Lieutenant-Commander Shibata approached the oblivious Agwiworld with the early afternoon sun behind his boat, a classic attack from out of the sun. Coupled with a heavy swell the big Japanese submarine’s approach behind the tanker was unobserved. The first the Agwiworld and her captain, Frederick Goncalves, knew of the presence of the Japanese submarine was the thump of the impact and explosion of a 140mm armour-piercing shell in the ship’s stern. The I-23 moved into a firing position to enable her deck-gunners to blast the tanker to scrap. However, due to the rough conditions, the Japanese sailors experienced difficulties loading and aiming the deck-gun. The I-23’s deck was awash as the boat rolled and pitched in the swell. Captain Goncalves did everything he could to make the Agwiworld as difficult a target as possible to hit, zigzagging through the whistling shells, probably eight or nine of them, before the I-23 was seen to submerge. Commander Shibata had clearly lost interest in his prey. The heavy seas and the fact that in order to achieve a good attacking position he would have had to have driven the I-23 harder would have risked the lives of his gunners, who could have been swept overboard. A further factor which precluded a more determined assault on the tanker originated in the submarine’s own radio room. The operator alerted his captain to the fact that the enemy ship had reported the Japanese submarine’s attack to the US Navy, and assistance in the form of anti-submarine assets were undoubtedly on their way.

Shibata and the crew of the I-23 were frustrated as they departed from the scene of their first attack on an American ship to search out further prey. Some time later Shibata encountered the 2,119-ton American merchant ship Dorothy Phillips. Employing an identical method of attack as that used against the Agwiworld, gunners again pumped high velocity armour piercing rounds into the hapless steamer. Although the I-23 successfully disabled the Dorothy Phillips’s steering by wrecking the ship’s rudder with a shell strike, a torpedo attack was not pressed home, presumably because the sea conditions were still unfavourable. Nevertheless, the Dorothy Phillips eventually ran aground so Shibata had scored a victory of sorts.

Lieutenant-Commander Kanji Matsumura was an experienced submarine skipper, having previously commanded the RO-65, RO-66 and RO-61 before commissioning the I-21 into service on 15 July 1941. As with the other boats assigned to operations along the United States west coast, the I-21 was formerly part of the submarine task group that made up an element of ‘Operation Z’. On 9 December the submarine I-6 had reported a Lexington-class aircraft carrier and two cruisers heading north-east. The Japanese were well aware that although they had scored a notable victory against the US Pacific Fleet’s battleship squadron they had failed to sink or damage a single American aircraft carrier. It was imperative that American carriers be sunk or damaged wherever found for the Japanese themselves had already demonstrated the power of naval aviation in this new conflict, and the days of the big-gun battleship appeared to be numbered. Vice-Admiral Shimizu at 6th Fleet Headquarters at Kwajalein, on receiving the intelligence report from the I-6, immediately ordered all submarines not involved with the launching of the midget submarines during the Pearl Harbor operation, known as the Special Attack Force, to proceed at flank speed and sink the American carrier. The I-21 was included in Shimizu’s force sent to intercept the vessel later identified as the USS Enterprise, but her progress was hampered by problems with the submarine’s diesel engines and electrics. Carrier-based Douglas SBD Dauntless aircraft spotted the I-21 on the surface on a number of occasions, necessitating Matsumura to crash-dive. Matsumura became increasingly fed up with constantly being forced beneath the waves by patrolling American aircraft. He decided upon a bold course of action – to remain surfaced and take on the enemy aircraft with his anti-aircraft armament. Motoring on the surface at 1 p.m. on the afternoon of 13 December a lone Dauntless attacked the submarine from the port side, but the accuracy of the Japanese anti-aircraft barrage caused the pilot to abort his attack run and go around for a second attempt. Diving towards the port side of the submarine again the American aircraft released a single bomb which slammed into the sea close to the I-21, but which failed to detonate.