The Korean War was a war between North and South Korea that took place about 1950. Following World War II, Japan withdrew from Korea. The peninsula was divided between the Communists in the north backed by the Soviet Union, and the Capitalists in the south, backed by the United States, Great Britain, and France. North Korea then attacked South Korea, overruning the South Koreans and their allied UN forces and forcing them southwards into a small perimeter around Pusan, the only remaining deepwater port. The UN counterattacked under General MacArthur with landings around Inchon and a breakout from Pusan, and the North Koreans were routed.
The UN pursued northwards through freezing temperatures almost to the border with the Chinese, at the Yalu River. The Chinese entered the war, attacking in overwhelming numbers and forcing the UN back to about the original North-South border. Several years of stalemate ensued until an armistice was signed. The two Koreas are still officially at war.
Air battles took place between Sabres and Soviet-manned MiGs in MiG Alley.
The fighting retreat from the Chosin Reservoir was one of the greatest battles in the United States Marines' history.
The war was part of a larger American policy of containment, where small countries were supported in their efforts to prevent the spread of communism. This was to prevent a domino effect.