Operation Vengeance was essentially America’s revenge against Japan for the bombing of Pearl Harbor (or at least part of the revenge). The attack on Pearl Harbor was masterminded by Admiral Isoroku Yamamoto.
In the spring of 1943, Yamamoto was seeking to build moral among Japanese forces following their defeat at the Battle of Guadalcanal. American intelligence had broken the Japanese code and discovered Yamamoto’s itinerary. President FDR then personally ordered Operation Vengeance with the aim of killing Yamamoto as revenge for Pearl Harbor.
On April 18th, 18 American P38 fighter planes took off to intercept the the Admiral over Bougainville Island. A dogfight occurred in the sky, and Yamamoto’s plane was sent crashing down into the jungle below with him in it.