Since the North Korean invasion of the South on June 25, 1950, United Nations forces had managed to reverse the situation by September, retaking the capital of Seoul and driving a routed Korean People’s Army (KPA) back into its home territory.
The newly established communist China, however, could not tolerate a united pro-Western Korea on its Manchurian border, and in late October, the so-called People’s Volunteer Army (PVA) intervened in the conflict, crossing the Yalu River into Korea.
By mid-November the PVA had thrown the U.N. forces back, retaking Seoul and giving the North Koreans a chance to regroup. In February 1951, however, the Chinese supply lines were overextended and recovering U.N. forces brought their offensive to a halt in the Battle of Chipyong-ni on Feb. 13-14 and Operation Killer nearly a week later.
