The 847th Bombardment Squadron is a former United States Army Air Forces unit that was originally activated as the 421st Bombardment Squadron. Its last assignment was with the 489th Bombardment Group at Great Bend Army Air Field, Kansas where it was inactivated on 28 March 1945. As the 20th Antisubmarine Squadron, the squadron performed antisubmarine patrols in 1942 and 1943. After reforming as a heavy bomber squadron, it engaged in the strategic bombing campaign against Germany in the European Theater of Operations until returning to the United States in late 1944. The squadron was inactivated while its parent group was training as a very heavy bombardment unit.