Mogami as CAX

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Mogami as CAX

The four ships of the class were: Mogami, laid down in 1931; Mikuma, laid down in 1931; Suzuya, laid down in 1933; Kumano, laid down in 1934. The pause between the first two and the second pair is due to the problems encountered, as described above. The first pair were completed in 1935, and the second pair in 1937, all with their initial battery of 15-6.1in guns. The last two ships were laid down in 1942, but never completed. Ibuki began conversion to a light aircraft carrier after 1943, but was suspended in March 1945 when 80% complete. Hull No. 301 was canceled shortly after being laid down, and never received a name.

After her 1939 modification, Mogami made 34.9kts on trials at 13,668t. Typical wartime modifications included an increase in light AA battery. Suzuya and Kumano had 20-25mm in 1943, 30-25mm in Jan. 1944, and 50-25mm by July 1944.

The Japanese 8in/50 gun fired a 277lb AP shell at 2,756fps MV to a range of 32,150yds at 40 degrees of elevation (for complete specifications on all IJN guns, follow my Hot Link to Jonathan Parshall’s “Imperial Japanese Navy” page). The Japanese 8in AP shell proved disappointing in service, often failing to explode. It is perhaps worth mentioning that, throughout the war, the gunnery of Japanese heavy ships generally failed to meet expectations.

On the plus side, the Mogami class, like most Japanese cruisers, had a very heavy battery of torpedo tubes. And they carried the 24in Type 93 “Long Lance” oxygen fueled torpedo. The Type 93 had a range of 22,000yds at 49kts, three times that of contemporary U.S. 21in torpedoes, and over twice that of the British Mk IX. It delivered a 1,210lb explosive charge (about 50% heavier than the Mk IX). Furthermore, Japanese ships carried reloads for their torpedo tubes (a torpedo attack was a one shot proposition in other navies). In the pre-war years, the IJN worked hard to develop and hone superior torpedo attack techniques (this at a time when the USN was determining that cruisers should not carry torpedoes!). All of this paid off in a big way with spectacular victories in the Java Sea, at Savo (the worst defeat in U.S. naval history), and other places.

All led active wartime careers, Mogami’s being particularly interesting. On 28 Feb 1942 she was covering transports off Java as part of the Western Covering Group, when the cruisers USS Houston and HMAS Perth (having survived the Battle of Java Sea the day before) attacked the convoy. Mogami and Mikuma engaged the allied cruisers and, helped by Japanese destroyers in the area, sank them both in the Battle of Sunda Strait. The Japanese cruisers’ gunfire on this occasion was reported as not being particularly accurate, but overwhelming. Both allied cruisers were ultimately sunk by torpedoes, after being shattered by gunfire.

By April 1942 she was in the Indian Ocean supporting the Japanese fast carrier task force that was mauling the Royal Navy’s Indian Ocean squadron and sinking the carrier Hermes, and heavy cruisers Cornwall and Dorsetshire.

All four sisters were in the Battle of Midway, in early June 1942. After the debacle of the carrier battle, Admiral Yamamoto canceled a scheduled bombardment of Midway Island by the four heavy cruisers of the Mogami class. Mogami and her sisters were retiring at high speed when Mogami failed to react to a sudden sharp course alteration, and rammed Mikuma. Mogami’s bow was smashed, and Mikuma had a ruptured fuel tank. Their speed was seriously reduced, and while Suzuya and Kumano fled safely beyond the range of U.S. planes, the morning found Mogami and Mikuma limping along, trailing oil, and still within range. Planes from Midway located and attacked the damaged cruisers, and planes from Spruance’s carriers sank Mikuma and gave Mogami a pounding.

As a result of Midway, Mogami was out of action until April 1943, and when she emerged from the repair yard she had been completely rebuilt again, this time into a hybrid cruiser-seaplane carrier. “X” and “Y” turrets were removed and the aft third of the ship became an aircraft handling deck, with two catapults. She could carry 11 seaplanes. Due to the shortage of aircraft, she never carried more than 6. She was sent to Rabaul, where she was again damaged by U.S. carrier planes.

Her final major engagement was the night Battle of Suragao Strait, part of the overall operation known as the Battle of Leyte Gulf, in late October 1944. The Japanese plan, named SHO-1, was intended to break up the U.S. invasion of the Philippines. It was put into operation as soon as the U.S. amphibious invasion commenced at Leyte.

In brief, this complex plan consisted of three major naval forces, a Northern Force, a Center Force, and a Southern Force. The Northern Force of 18 ships including the four available aircraft carriers (stripped of their planes), two hybrid battleship-carriers, 3-CL, and 9-DD, was to slip into position about 200 miles north and east of Cape Engano, Luzon. It’s job was to decoy the U.S. 3rd Fleet (Admiral Halsey’s fast carrier task force, which was covering the landings) north and away from the beachhead at Leyte Gulf. It was accepted that the Northern Force would be decimated.

This sacrifice was made to allow the Center Force (5-BB, 10-CA, 2-CL, 14-DD), the main battle fleet, access to Leyte Gulf. They were to steam northeast from Brunei Bay, Borneo, weaving through the middle of the Philippine archipelago, and then through San Bernardino Strait to loop around Samar, and enter Leyte Gulf from the east (Pacific Ocean) side. Once in the Gulf, they would destroy the American transports and supply ships and shell the beachhead.

The Southern Force, split into two autonomous groups (2-BB, 1-CA, 4-DD + 2-CA, 1-CL, 4-DD), was to enter Leyte Gulf from the south, through Suragao Strait, catching the U.S. ships in the gulf in a pincer. The Center and (dual) Southern forces would be entirely without air cover, which is why the Northern Force had to be sacrificed to get the American fleet carriers out of the area. They were scheduled to converge on Leyte Gulf about dawn on October 25th, 1944.

Mogami was assigned to the Southern Force (under the command of Admiral Nishimura), along with battleships Fuso and Yamashiro, and four destroyers (including the famous Shigure). Battleship Fuso and three of the destroyers were sunk by torpedoes fired by U.S. destroyers while transiting Suragao Strait. That left only Yamashiro (slowed by two torpedo hits to 12kts), Mogami, and Shigure to face the assembled U.S. battle line (forewarned by aerial reconnaissance, and kept up to date on Japanese movement through the Strait by the destroyers and PT boats), which waited at the entrance to Leyte Gulf.

In this unequal night battle, the three Japanese ships faced 6-BB, 4-CA, and 6-CL, supported by destroyers, placed in such a way as to “cross the T” of the Japanese ships attempting to exit Suragao Strait and enter Leyte Gulf. When the shooting started at 3:51 AM on 25 October, Yamashiro and Mogami became the focus of an overwhelming volume of fire. Hundreds of rounds of 14in and 16in battleship shells, plus countless 6in and 8in cruiser rounds engulfed the two ships.

Shigure managed to dodge salvoes, receiving only one hit. Mogami and Yamashiro returned fire as best they could. Yamashiro, lacking radar, fired at the only ships she could see, the right flank cruisers, while her secondary batteries fired at destroyers closing in for torpedo attacks, eventually scoring a hit on the Grant. At 3:55 AM Mogami turned away; at 4:01 AM she launched torpedoes, which missed. Shigure reversed course to retire. By that time, Yamashiro was on fire from stem to stern, still firing doggedly.

At 4:02 AM Mogami was struck by a salvo from the heavy cruiser Portland which killed her Captain, and all the officers on the bridge. About the same time she was hit in the boiler and engine rooms, and slowed to a crawl, on fire, retiring back up Suragao Strait. At 4:09 AM Admiral Oldendorf, the American commander, ordered cease fire, to avoid hitting his own destroyers. Yamashiro managed to increase speed to 15kts, and turned 90 degrees to port. At 4:11:30 she was hit by two torpedoes, and began listing sharply. Her list increased to 45 degrees, and her Captain ordered “abandon ship”. She sank about 4:20 AM; there were only a few survivors.

The second part of the Japanese Southern Force, under Admiral Shima, and including heavy cruiser Nachi, was still coming down the strait, while Mogami, heavily ablaze, was groping her way back up. Nachi incorrectly plotted Mogami’s course and speed (evidently they thought Mogami was stopped), and the two collided. They got untangled, and Admiral Shima ordered his formation to reverse course and retire, accompanied by Shigure. Apparently he did not like the looks of what he was steaming toward.

At 4:32 AM Admiral Oldendorf ordered heavy cruisers Portland and Louisville plus light cruiser Denver and some destroyers into the Strait to “clean up” any Japanese cripples. Dawn came, and at 5:30 AM the American cruisers caught up with Mogami. They pumped more shells into her, reported that she was heavily on fire, but somehow she worked up speed and escaped. The American commander was reluctant to follow her too far for fear of Japanese torpedo attack. Mogami also managed to beat off two attacks by PT boats that morning. But about 8:45 AM she was found and finally sunk by Avenger torpedo bombers operating from the escort carriers in Leyte Gulf.

Suzuya and Kumano were part of Admiral Kurita’s Center Force in the Leyte Gulf operation. The Center Force was hit first on 23 October by two submarines that sank two heavy cruisers and disabled a third. Then on the 24th, the Center force came under intense air attack by planes from Admiral Halsey’s fast carrier groups, while in the Sibuyan Sea.

In the Battle of the Sibuyan Sea, the super battleship Musashi was sunk, and another heavy cruiser disabled, and the Center Force reversed course. Admiral Kurita reassembled his remaining ships, and resumed course for Leyte Gulf. He was now about seven hours behind schedule, but the American planes had reported him withdrawing. His appearance in Leyte Gulf the next day would be a complete surprise.

The Battle of Samar is the famous engagement that resulted when Kurita’s Center Force entered Leyte Gulf on the 25th and met Admiral Clifton Sprague’s escort carrier group and its covering destroyers, called “Taffy 3”. Taffy 3 comprised 6-CVE, 3-DD, and 4-DE.

Taffy 3 was the first American force encountered by Kurita when he entered Leyte Gulf. They got air support from the nearby Taffys 1 and 2. In the wild melee that resulted, Suzuya was bombed and seriously damaged. Her sister Kumano was torpedoed by destroyer Johnston. Both cruisers dropped out of the battle; Suzuya succumbed to her damage and sank. Another heavy cruiser, Chokai, was sunk by 10 bombs (and 6-5in shell hits from the CVE White Plains, adding insult to injury). Ultimately, the Japanese battle fleet was driven off in confusion by destroyers and furious air attacks from the “jeep” carriers. The Battle of Samar cost the Center Force 3-CA. They sank 2-CVE, 2-DD, and 1-DE.

Meanwhile, Admiral Ozawa’s Northern Force, the once invincible fast carrier task force of the Imperial Navy, now reduced to playing the part of a decoy, was attempting to lure the overwhelming strength of Admiral Halsey’s Third Fleet north, and away from the Center Force and Leyte Gulf. And it worked! Halsey steamed north and smashed the Northern Force in the Battle off Cape Engano on 25 October, but left Leyte Gulf open to the Center Force. Only the desperate courage of the little Taffy groups stopped the Center Force from reaching the transports and supply ships at the Leyte beachhead. The decoy operation cost the Japanese 1-CV, 3-CVL, 1-CL, and 1-DD.

Kumano, after being torpedoed by a destroyer at the Battle of Samar, was subsequently torpedoed by a submarine. She was finally sunk a month later by aircraft from the carrier Ticonderoga at Dasol Bay, in the Philippines, on 25 November 1944. So the Philippines campaign took the last three of the class.

After the series of battles (Sibuyan Sea, Suragao Strait, Samar, and Cape Engano) known collectively as Leyte Gulf, the Imperial Japanese Fleet ceased to exist as a unified fighting force. The remaining heavy ships were picked off one or two at a time, mostly by aircraft, but a few by submarines.

The record of the Mogami class ships in surface engagements was very good. They out gunned the heavy cruisers of all other nations. Their heavy torpedo and gun batteries served them well in the days before the U.S. Navy gained absolute air superiority. Their very high speed made them good escorts for the fast carrier task forces. They were well protected, and proved they could take a lot of punishment. Aesthetically, with their trunked funnel, tower superstructure, heavy tripod mainmast, and proliferation of turrets, they just looked mean.

Forschungsmitarbeiter Mitch Williamson is a technical writer with an interest in military and naval affairs. He has published articles in Cross & Cockade International and Wartime magazines. He was research associate for the Bio-history Cross in the Sky, a book about Charles ‘Moth’ Eaton’s career, in collaboration with the flier’s son, Dr Charles S. Eaton. He also assisted in picture research for John Burton’s Fortnight of Infamy. Mitch is now publishing on the WWW various specialist websites combined with custom website design work. He enjoys working and supporting his local C3 Church. “Curate and Compile“
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