The Battle of Buenaventura was a twelve-day engagement during the Pacific War at Buenaventura, Colombia in August and September of 1925 between the Japanese 10th Imperial Regiment of the XII Army and the Allied Powers, consisting mostly of Colombia, Brazilian and Mexican volunteers, and the 8th Battalion of US Army Engineers, who were serving as advisors to the Colombians in technical matters. The battle was part of the broader Panama campaign, and was designed by the Japanese as a strategic feint to open up a second defensive front for the Colombians, who were already stretched thin but had resiliently prevented Japanese victory at the Canal.
Despite overwhelming Japanese forces, the defenses at Buenaventura held true, and the Japanese were unable to establish a firm beachhead despite three attempted landings and one successful landing whose participants were eventually forced to surrender. It was the first major defeat for the Japanese in the course of the war, leading the Japanese to remove their forces from Panama a week later and fully withdraw their naval presence from Colombian waters in mid-October. The victory at Buenaventura is generally regarded as being critical to the overall strategic victory at Panama, and in fact the entire Pacific War.