She was laid down at Yokosuka in May 1940 as the third Yamato-class battleship, meant to carry 18.1-inch guns into a decisive surface battle that never came. After Midway cost Japan four carriers in a day, the half-built hull was converted instead. Shinano was commissioned on November 19, 1944 as the largest aircraft carrier in the world. Ten days later the USS Archerfish put four torpedoes into her. She went down with about 1,400 sailors, havin…