What if some of the large ocean liners such SS Normandie or SS Breman of the 20s and 30 were converted to aircraft carriers for use in World War Two? They were large and fast vessels. Japan laid down the Hiyo class as ocean liners, I don't believe they ever served as such. Italy started converting SS Roma, but never finished her. I know some of the ocean liners served as fast troop carriers, but others were laid up.