The Raid on Koiari was a battle that occurred between 28 and 29 November 1943 in the Pacific theater of World War II between American and Japanese forces. Part of the Bougainville campaign, the raid involved a landing by a battalion-sized force of United States Marines to harass Imperial Japanese Army troops on Bougainville Island. The raid was a failure for the Americans as they were attacked by a larger-than-expected Japanese force and as a result the Marines were withdrawn from the beachhead without having achieved any of their objectives.

The Battle of Piva Forks, also known as the Battle of Numa–Numa Trail, was an engagement that took place during the Bougainville campaign in World War II. Occurring between 18 and 25 November 1943 on Bougainville Island in the South Pacific, the battle involved troops from the United States Marine Corps and the United States Army fighting against Imperial Japanese Army forces and took place amidst the context of the expansion of a beachhead that US forces had established around Torokina on the western side of the island.