The Battle of Kaiapit was an action fought in 1943 between Australian and Japanese forces in New Guinea during the Markham and Ramu Valley – Finisterre Range campaign of World War II. Following the landings at Nadzab and at Lae, the Allies attempted to exploit their success with an advance into the upper Markham Valley, starting with Kaiapit. The Japanese intended to use Kaiapit to threaten the Allied position at Nadzab, and to create a diversion to allow the Japanese garrison at Lae time to escape.