The Korean War (1950–1953) saw the hastily formed 1st Provisional Marine Brigade holding the line at the Battle of Pusan Perimeter, where Marine helicopters (VMO-6 flying the HO3S1 helicopter) made their combat debut. To execute a flanking maneuver, General Douglas MacArthur called on Marine air and ground forces to make an amphibious landing at the Battle of Inchon. The successful landing resulted in the collapse of North Korean lines and the pursuit of North Korean forces north near the Yalu River until the entrance of the People's Republic of China into the war. Chinese troops surrounded, surprised and overwhelmed the overextended and outnumbered U.S. forces. However, unlike the Eighth Army, which retreated in disarray, the 1st Marine Division, while attached to the Army's X Corps regrouped and inflicted heavy casualties during their fighting withdrawal to the coast. Now known as the Battle of Chosin Reservoir, it entered Marine lore as an example of the toughness and resolve of the Marine. Marines would continue a battle of attrition around the 38th Parallel until the 1953 armistice.