What division of the American armed forces fought the Imperial Japanese Army, also know as the "Dai-Nippon Teikoku Rikugun", or "Army of the Greater Japanese Empire", at Bougainville during World War Two?
Battle of Hellzapoppin Ridge and Hill 600A: The Battle of Hellzapoppin Ridge and Hill 600A was a series of engagements fought in mid-December 1943 on Bougainville between forces of the United States Marine Corps and the Imperial Japanese Army. Imperial Japanese Army: The Imperial Japanese Army (IJA; 大日本帝國陸軍 "Dai-Nippon Teikoku Rikugun"; "Army of the Greater Japanese Empire") was the official ground-based armed force of the Empire of Japan from 1868 to 1945.
Marine Corps