The submarine phase of Operation A-GO had completely miscarried. Not only were seventeen submarines lost, but no submarines would now be available for quick action against the U.S. fleet off the Marianas. The destruction of the NA line and other losses in the area also tended to lead Japanese officers back to their preconceived opinion that any American attack would be launched at the Palaus.
The Japanese were now rapidly becoming aware that a major American offensive was at hand. But where? Even with the submarine losses south of Truk indicating a drive west from there, more substantial evidence was needed. Task Group 58.6, consisting of the carriers Essex, Wasp, San Jacinto, five cruisers, and twelve destroyers, struck Marcus on 19 and 20 May. Results were not overwhelming, but the attack prompted Admiral Toyoda to place TO-GO in motion. However, when TG 58.6 raided Wake on the 23rd it was obvious that these two forays were not full-scale attacks and Toyoda cancelled TO-GO.
Toyoda issued his preparation order for A-GO on 20 May. The Mobile Fleet was placed on a six-hour alert. Falling back on one of their favorite tactics, the “bait” force, the Japanese commanders ordered the battleship Fuso, cruisers Myoko and Haguro, and a pair of destroyers to be ready to sortie as a decoy force. They were to lure the Americans into the Palau–Ulithi area where they could then be destroyed by naval and air forces concentrated there. Finally, Base Air Force was ordered to intensify its reconnaissance efforts.
Base Air Force conducted several reconnaissance flights over American bases. On 27 May one plane flew from Truk via Buin (thought by the Americans to be knocked out) to Tulagi, where Rear Admiral Richard L. Conolly’s Southern Attack Force was staging for the Guam landing phase of the Marianas invasion. Two other Truk-based planes staged through Nauru to take a look at Majuro and Kwajalein, where most of the invasion forces were gathering. The day before TF 58 sortied from Majuro another intrepid pilot took a peek at the lagoon and reported an impressive array of warships there. The Japanese now had the Americans located, but they were not quite sure of what to do next.
Following the receipt of “Start A-GO,” which actually meant “Begin preparations,” Admiral Ozawa held a meeting on his flagship Taiho for all his commanders. He reminded them that the coming action was to be decisive, and that they were to press on despite any damage suffered. Regarding the latter point, Ozawa declared that for A-GO to succeed, individual units had to be considered expendable. The officers present also discussed proposed tactics for the battle. A massed grouping of carriers much like the disposition used by the Americans was considered, or an “encirclement” using an inverted-V arrangement of three groups. But the final disposition chosen for the Mobile Fleet involved dividing the force into a Main Body and a heavily armed Vanguard.
The Japanese now watched and waited. Then came the invasion of Biak on 27 May. The Japanese high command felt that this move should not go unchallenged. In the first place, the loss of the three airfields on this island off the coast of New Guinea would be a serious blow to the air units of A-GO. The Japanese also reasoned that an attempt by them to recapture Biak would lure the U.S. fleet into “The Decisive Battle near Palau.” But the Combined Fleet intelligence officer, Commander Chikataka Nakajima, was not convinced Biak was the major offensive. He thought the landings were just a subsidiary operation and the main American effort would be aimed at the Marianas. His superiors did not agree with him, though, and the Japanese prepared a relief operation for Biak designated Operation KON. The KON plan called for warships to transport about 2,500 troops to Biak from Mindanao. The battleship Fuso, the heavy cruisers Myoko and Haguro, and five destroyers were to act as the screen for a transport section of one heavy and one light cruiser, and three destroyers.
The movement of the enemy ships, coming mainly out of Tawi Tawi, did not escape notice. Allied intelligence officers, using “Magic” intercepts, already knew that a landing attempt would be made on Biak around the fourth or fifth of June and that the Fuso, Myoko, and Haguro would be in the force. The reports by the submarines Cabrilla and Bluefish of enemy vessels leaving Tawi Tawi merely confirmed the “Magic” reports.
The transport section, now augmented by two minelayers and a small transport, picked up its troops at Zamboanga on 31 May and proceeded to Davao, where it rendezvoused with the heavy cruisers and three destroyers. The units then headed for Biak, the Fuso and two destroyers taking a more northerly course. On the morning of 3 June the submarine Rasher spotted part of the force and sent off a contact report. The message was intercepted by the Japanese, who were disturbed at being discovered so far from their target. When a Wakdebased PB4Y began shadowing them, the Japanese decided to call off the attempt.
But this abortive effort would not end happily for the Japanese. While the transport section proceeded to Sorong, on New Guinea’s western tip, to disembark troops, the Fuso, Myoko, Haguro, and two destroyers retired to Davao. As this force approached Davao on the night of 8 June, they ran into the path of the submarine Hake. Commander John C. Broach waited until a destroyer crossed his sights, then fired a spread of torpedoes that ripped open the 2,077-ton Kazagumo and sank her.
While the first attempt to reinforce Biak by sea had stalled, action in the air over the island had heated up considerably. Since the Japanese had been anticipating that the next major U.S. offensive would be in the Carolines—Palaus sector, much of their air strength was situated in or near this region. When the Biak landings “confirmed” their suspicions, they began rushing planes in to reinforce their 23rd Air Flotilla. A number of these planes came from the Marianas—reducing the air strength there at a time when they would most be needed.
This one fact illustrates the effectiveness of the Joint Chiefs’ concept of a dual thrust across the Pacific. No longer could the Japanese mass their forces in a particular area against an enemy thrust, for now they could be outflanked by another enemy movement.
A number of air strikes were flown against U.S. positions on Biak and Wakde; one attack in particular, on 5 June at Wakde, was very successful. But the Japanese could not keep up the intensity of their attacks and in the process lost planes that could have been used more profitably elsewhere. Also, quite a few pilots came down with malaria at this time, greatly limiting their usefulness.
The Japanese were not about to give up on Biak, though, and a second attempt to reinforce it was quickly mounted. On 7 June Rear Admiral Naomasa Sakonju led a force of six destroyers, distantly screened by two cruisers, on the reinforcement mission. Three destroyers carried six hundred troops, while the remaining destroyers provided an escort and also towed a landing barge each.
Sakonju’s second effort (he had led the first attempt) was to be even less successful. On the 8th ten B-25s from Hollandia, escorted by P-38s, spotted Sakonju’s ships sliding in toward Biak. In a low-level bombing and strafing attack, the B-25s sent the 1,580-ton Harusame to the bottom and damaged the Shiratsuyu, Shikinami, and Samidare. Sakonju pressed on, but not for long. At 2340 a lookout on one of Sakonju’s ships picked up an Allied cruiser and destroyer force, led by Rear Admiral Victor A. C. Crutchley, RN, which was out looking for just these ships.
Sakonju decided that discretion was the better part of valor. After casting off the barges, his force fired a volley of torpedoes at the Allied ships and then high-tailed it to the northwest. Involved in a stern chase and having to dodge torpedoes occasionally, the Allied destroyers were unable to close the distance enough to be effective. The Shigure was hit five times by 5-inch fire and the Shikinami also had some casualties, but that was the extent of damage to both sides. Most of the troops—who must not have been very happy about what was taking place around them—were taken back to Sorong. The second attempt to reinforce Biak had been turned back.
While the Japanese were vainly trying to reach Biak, a lone U.S. submarine was making her presence felt near Tawi Tawi. Commander Samuel D. Dealey was on his fifth patrol in the Harder. This patrol he had been assigned a dual mission: scout Tawi Tawi and pick up a group of guerrillas on northeast Borneo.
As the Harder was transiting Sibutu Passage (just south of Tawi Tawi) on the night of 6 June, a convoy of three tankers and two destroyers was picked up. Closing the convoy on the surface, the sub was suddenly spotlighted for the nearest destroyer, when the moon broke through the clouds. The Japanese destroyer charged in for an “easy” kill. Dealey waited until the enemy ship was only 8,500 yards away before submerging. When the ship got within 1,100 yards, Dealey let her have three “fish” from the stern tubes. The Minazuki, a 1,590-ton vessel, was stopped cold by two torpedoes, blew up, and went down fast. A second try at the convoy by the Harder was frustrated by the other destroyer, and Dealey turned back toward Sibutu Passage.
Shortly before noon the next day, Dealey saw another destroyer in the Passage. And the destroyer saw the Harder! This time Dealey let the 2,077-ton Hayanami come in close to point-blank range—650 yards—before firing three torpedoes “down the throat.” Two of them disembowled the Hayanami, and nine minutes after the first sighting she sank, stern first. But Dealey and the Harder were not home free. A second destroyer came boiling over to the spot and spent the next two hours rolling depth charges around the sub. None hit, but when six more Japanese destroyers showed up, Dealey decided it was time to leave. He cleared the area and on the night of 8 June picked up his group of guerrillas. He then returned through Sibutu Passage and took up station off Tawi Tawi.
Two more Japanese destroyers showed up in the Harder’s periscope the following night. Dealey made a submerged approach on the ships and when the targets overlapped, he fired four torpedoes. Two hit the 2,033-ton Tanikaze, which literally fell apart. The other two “fish” were thought to have hit the second destroyer, but there is no record of this ship being lost or even damaged.
Dealey and the Harder had made a big dent in Ozawa’s destroyer forces. Three destroyers had been sent to the bottom in four days by “The Destroyer Killer” (as Dealey was later nicknamed). The U.S. submarines congregated around Tawi Tawi had hurt Ozawa and, thus, Operation A-GO. Along with the destroyers Dealey had sunk, several others had been lost or would soon be. Destruction of these destroyers would mean that the Mobile Fleet would be inadequately screened by these critically important, versatile ships during the coming battle. It was a situation other American submarines would take advantage of in the Philippine Sea.
In the meantime, following the second failure to reinforce Biak, Ozawa was more determined than ever to force his way to the island and land troops that would push the invaders back into the sea. To this end he assembled a new force to carry out Operation KON. It was not a puny force. Included in it were the superbattleships Yamato and Musashi, three heavy and two light cruisers, seven destroyers, two minelayers, and a number of support and transport vessels.
Under the command of Vice Admiral Matome Ugaki, this force sortied from Tawi Tawi on the afternoon of 10 June. Their departure was noted by Sam Dealey. As the Harder closed in for an attack, the sub’s periscope was seen and a destroyer charged in. Dealey was not impressed and waited for the enemy ship to close the range. At 1,500 yards three torpedoes were fired “down the throat.”
As the Harder went deep, a series of explosions were heard. Dealey thought he had gotten another destroyer, but Japanese records do not confirm this. If not sunk, this unidentified destroyer must have been badly damaged. The other escorts and covering aircraft were not about to let the Harder off the hook, but she did escape after undergoing a succession of furious counterattacks. After dark, Dealey was able to surface and send a contact report about the enemy’s departure from Tawi Tawi.
The Japanese ships continued on to Batjan, just south of the island of Halmahera, where they arrived on the 11th. The run to Biak was scheduled to be made on the 15th. This time the troops were to be landed at all costs, and the big guns of the heavy ships were to be used in a smashing bombardment of U.S. positions on the island.
But fate, and the U.S. Fifth Fleet, were again to stall the reinforcements for Biak. On the 11th and 12th TF 58 planes pounded Saipan and Guam. The Japanese now realized they had been outfoxed; the Americans were aiming for the Marianas, not the Palaus. At 1830 on 12 June Admiral Toyoda ordered the start of A-GO. Operation KON, although only “temporarily” called off, was never resumed.
Admiral Ozawa’s Mobile Fleet began moving out for the fateful meeting in the Philippine Sea.