Battle of Koromokina Lagoon

The Battle of the Koromokina Lagoon was fought between the United States Marine Corps and Imperial Japanese Army forces on Bougainville Island. It took place on 7–8 November 1943 during the Bougainville campaign of the Pacific War. In response to the Allied landings on Bougainville at Cape Torokina, Japanese General Hitoshi Imamura, commander of the 8th Area Army at Rabaul, determined to launch a counterattack. Underestimating the size of the Allied landing forces, the Japanese dispatched a force of 850 soldiers to execute a counter landing to attempt to drive the Allied forces back into the sea. The Japanese soldiers landed from four destroyers near Koromokina Lagoon on the night of 7 November and engaged two battalions of U.S. Marines from the 3rd and 9th Marine Regiments under the command of Major General Allen H. Turnage. Over the next two days the Japanese attacks were defeated with heavy losses to the attackers. After the battle, Allied forces continued to expand their beachhead on Bougainville with the goal of constructing airfields to attack and neutralize Japanese forces located at Rabaul and nearby areas. Responding to the Allied landings on Bougainville at Cape Torokina on 1 November 1943, Japanese General Hitoshi Imamura—commander of the 8th Area Army at Rabaul—decided to send a force to counter the Allied landing. Imamura intended to deploy about 3,000 troops from Rabaul; however, US air and naval activity prevented this and limited the Japanese to a smaller force. The Japanese commander on Bougainville, Harukichi Hyakutake, dispatched a large group of reinforcements from the 23rd Infantry Regiment from the main Japanese position around Buin on the southern tip of Bougainville to assault the right flank of the Allied lodgment. Meanwhile, a force of 475 troops was dispatched from Rabaul to the Torokina area to conduct a counter-landing on the left flank in coordination with the assault on the right, while a further 700 were sent to reinforce the Japanese garrison at Buka.