Fighting under the name of hakkō ichiu a belief that the whole world should be united under the authority of a single emperor Japanese troops occupied almost 80% of the territories in Asia during the first years of the war. However from June 1942 to December of the same year Japanese control of the Pacific was challenged by Douglas MacArthur during the Guadalcanal campaign. Committing war crimes was one of the most horrific weapons their forces used to avoid defeat.