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. Although minor in terms of casualties and in comparison to other battles in the campaign, the battle was the last significant action undertaken by the 3rd Marine Division on the island before they were replaced by United States Army soldiers from XIV Corps. It resulted in the capture of the two positions by the Marines with the support of artillery and aircraft, and the withdrawal of the Japanese forces as the American perimeter, which had been established around Torokina, was expanded towards the Torokina River.