Japanese aircraft carrier Yonaga
Career (Japan)
Name: Yonaga
Laid down: 1937
Launched: 1939
Commissioned: 1941
Fate: Active
General characteristics
Displacement: 52,000 long tons
Length: 310 m (1000 ft)
Beam: 41 m (136 ft)
Draft: 10,5 m (34,5 ft)
Installed power: 212,000 shp
  • 6 × Kampon geared steam turbines
  • 10 × boilers
  • 6 × shafts
Speed: 32 kn
Complement: 4100

December 1941:

  • 16 × 127 mm (5 in) Type 98 dual purpose guns
  • 36 × 25 mm (1 in) Type 96 anti-aircraft guns
Aircraft carried:

126 December 1941:

The Japanese aircraft carrier Yonaga is a aircraft carrier of the Imperial Japanese Navy built during the mid-1930s. She was completed and commissioned just days prior the attack on Pearl Harbor 7 December 1941. With a total displacement on at least 52,000 long tons, she was the largest aircraft carrier ever built in the world at that time.


The Yonaga owed its existence to factional disputes amongst the Japanese Naval hierarchy over how best to bring an enemy navy to a "Decisive Battle" and defeat him soundly. In the late 1930's, large-caliber naval artillery aboard heavily-armored ships was still considered the arbiter of naval battles, but the growing ship-killing capabilities of the airplane, even single-engined ones aboard aircraft carriers, created a rival faction of adherents. Limited shipbuilding resources created strident arguments over where to place the faith in composing a victorious fleet of the future. Could size and quality trump quantity? The looming tensions with Western powers, who had their own large carriers, made war in the near future a strong possibility so a few shipbuilding 'deals' were made by the 'big gun' and 'fleet air' factions.

In the mid-1930s United Kingdom and the United States already had fast, giant aircraft carriers (HMS Incomparable and the Lexington class aircraft carriers) converted from battlecruisers, but the best Empire of Japan could do was the 42,000 long tons slower and less spectacular Japanese aircraft carrier Akagi. When Japan started building the three super-battleships of the Satsuma class battleship (70,000+ tons, 6 20" guns) in 1938, delays in securing sufficient quantities of heavy armor plate stalled progress. Rather than let the slipway remain idle, the carrier faction seized upon the opportunity to assert their will and build the world's largest and most powerful aircraft carrier.

To increase fineness ratio and accommodation, 130 feet were added to the hull amidships bringing the overall length to just under 1,000 feet. The extra length allowed additional boilers below decks for greater speed than the planned battleship, and various other improvements over the Shōkaku class aircraft carriers then building. Experience with other large battleship conversions made Yonaga's go rapidly, but she was still saddled with the same weakness of having the un-armored flight deck an integral part of the ship's structure. Lack of heavy armor gave Yonaga a medium displacement and high speed for her huge size. Ambitiously designed to accommodate 126 folding-wing aircraft, Yonaga operated only 102 of the relatively fixed-wing aircraft then in service. An island, on the port side like Akagis, was of a new, roomy design whose likeness became a feature on all subsequent fleet carriers, though mirrored onto the starboard side. A spacious suite invited an Admiral to hoist his flag aboard her (if he wasn't already duly impressed by Yonaga's power and size!).

When she worked-up just prior to the attack on Pearl Harbor, she had the largest aircraft complement of any carrier afloat in the world. Because of Yonaga's size and accommodation, two new aircraft concepts were tried out--the 'strategic reconnaissance plane' and the 'strategic fighter'. To better enable analysis of battlefield results, a speedy, long-endurance reconnaissance plane, the C6Y "Yamagumo", could linger over the battlefield, evade interception, and provide feedback to the mother carrier for the follow-up strike, something the typically dowdy floatplane scouts could not do while furtively trying to keep from getting shot down. Three were carried to provide an unbroken stream of information as they traded off overflight duties. In addition to the 'standard' complement of 27 each of dive, torpedo, and fighter aircraft such as the Shokaku carried, an additional 18 twin-engined, fast, heavily-armed MA6M "Misago"s (known as the "twin-engined Zero") were carried to sweep away or disrupt the enemy's air defense minutes prior to the attack group's arrival. The Yamagumo's inline V-12 engine required special 100-octane fuels that were ill-advisedly stored in barrels on the hangar deck, and the Misago's twin engines required twice the normal maintenance of other aircraft, making these two aircraft unpopular with the service crews despite their battlefield potential.

Yonaga and the Japanese aircraft carrier Owari (another battlecruiser conversion just completing) formed the Seventh Carrier Division. Fleet Admiral Chuichi Nagumo, in charge of the Hawaiian operation, was tempted to fly his flag aboard her, but preferred the China Incident veteran Akagi, leaving Rear Admiral Tamon Yamaguchi to command the 7th Carrier Division. Yonaga took aboard relatively inexperienced aircrews to Hawaii, along with the first air search radar aboard a Japanese ship. Yonaga's were the first Japanese aircraft over Hawaii, but her attack aircraft were only allowed to work over the 'easier' land targets and were the first aircraft to return to the Fleet. Yonagas primitive radar duly noted the returning aircraft but without IFF could not know that two American scout bombers from USS Constellation (CV-4) (undetected at sea) had boldly followed the air group back and mingled in the approach pattern. They attacked Yonaga just as she was launching her second wave and, using the giant Hinomaru painted on her forward flight deck as an aiming point, blew out her forward elevator. The bombs hit the barrels of 100-octane avgas, starting vicious fires that swept backwards, enveloping the entire carrier deck with thick, black smoke. The scouts reported the carrier aflame from end to end and presumably sunk. Yonaga pulled out of line and made a hasty 180-degree turn, then reversed at flank speed to prevent wind-driven flames from engulfing the ship and to stay with the Fleet despite the reduced speed. Plane handlers frantically turned 48 aircraft around to launch them into the wind off the stern, now cleared of smoke.

Yonaga was the only Japanese warship badly damaged during the attack on Pearl Harbor, and she made her way back to Japan for repairs. She was later a turning point for the Imperial Japanese Navy, that led Empire of Japan to victory, when she and three other aircraft carriers; the Japanese aircraft carrier Shōkaku, Japanese aircraft carrier Zuikaku, and the Japanese aircraft carrier Shōhō badly damaged a U.S. destroyer and sank two U.S. aircraft carriers; USS Enterprise (CV-6) and USS Lexington (CV-2) during the Battle of the Coral Sea. Yonaga took part in the largest naval battle of the war, the Battle of Midway. She and the largest Japanese aircraft carriers: Shōkaku, Zuikaku, Kaga and Akagi together with the Japanese battleship Super-Yamato (the world's largest, heaviest and most powerful battleship ever built) destroyed the entire U.S. Pacific Fleet, the worst naval defeat for the United States Navy.

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