In the mid-thirties the British and Americans had fast, giant aircraft carriers (HMS Incomparable and the USS Lexingtons) converted from battlecruisers, but the best Japan could do was the slower and less spectacular Akagi. When Japan started building the three super-battleships of the Satsuma class (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, Japan seized the opportunity to build the world's largest and most powerful CV.

To increase speed and accommodation, 130 feet were added to the hull amidships bringing the overall length to just under 1,000 feet. Experience with other large battleship conversions made Yonaga's go rapidly, but she was still saddled with the same weakness of having the unarmored flight deck an integral part of the ship's structure. Lack of heavy armor gave Yonaga a medium displacement for her huge size, and high speed. Ambitiously designed to accommodate 125 folding-wing aircraft, Yonaga operated only 98 of the relatively fixed-wing aircraft then in service. When she worked-up just prior to the Hawaiian Operation, she had the largest aircraft complement of any carrier afloat. An island, on the port side like Akagi's, was of a new, roomy design whose likeness became a feature on all subsequent fleet carriers, though mirrored onto the starboard side.

Yonaga and Owari (another BC conversion just completing) formed the 7th Carrier Division at the outbreak of war and took aboard inexperienced aircrews to Hawaii. Yonaga's planes were allowed to work over the "easier" land targets and were the first aircraft to return to the Fleet. Scout bombers from USS Constellation (undetected at sea) sighted and attacked Yonaga just before another launch and blew out her forward flight deck and elevator. Yonaga made a hasty 180-degree turn and reversed at flank speed to prevent wind-driven flames from engulfing the ship and to stay with the Fleet. Plane handlers frantically turned 48 aircraft around to launch them "into the wind" off what was now the stern. The next American attack sank the giant smoking carrier but they erroneously reported it as a different one because it had a 'starboard' island.

Though Yonaga's loss was a great blow to the Japanese, the four American CV's reported sunk off Hawaii (actually only two, plus one severely damaged, plus the target-ship Utah mistaken for a carrier with her reinforced deck planking) and the destruction of other surface ships gave rise to a fatal optimism for the Japanese. Most large CV's built thereafter had armored decks but couldn't handle more than 65 aircraft, so Yonaga remains the most powerful aircraft carrier ever built by the Japanese.

Admiral's note: Yonaga was inspired by Peter Albano's book The Seventh Carrier about a similar fictional carrier having armored decks and 125 aircraft that got trapped in an ice cave just before the Hawaiian Operation and didn't get thawed out until 1981 to complete her mission as assigned 40 years before!! Albano's pre-war Yonaga would have surpassed the capabilities of even the post-war USS Midway class. That would have been too advanced even for my Grand Fleet assumptions, so I toned down my Yonaga to meet a more reasonable Japanese capability.