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. 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.