Premise: Zuikaku (Japanese: 瑞鶴 "Auspicious Crane") was a "Shōkaku"-class aircraft carrier of the Imperial Japanese Navy. Her complement of aircraft took part in the attack on Pearl Harbor that formally brought the United States into the Pacific War, and she fought in several of the most important naval battles of the war, before being sunk during the Battle of Leyte Gulf.
Hypothesis: The Shokaku class aircraft carriers were part of the reason the United States was brought into the Pacific War.