Korean War: Background
After Japan was defeated by the Allies in World War II (1939-45), it lost control of Korea, which it had ruled as a colony since 1910. Korea was divided into two occupations zones, with the Soviet Union administering the area north of the 38th parallel and the United States administering the area south of the 38th parallel. The arrangement was intended as temporary; however, after plans to establish a national government failed, two separate nations formed in 1948: the Communist-backed Democratic People’s Republic of Korea (North Korea) and the Western-aligned Republic of Korea (South Korea). Border clashes soon broke out between the two Koreas, each of which claimed sovereignty over the entire peninsula.
The Korean War began on June 25, 1950, when North Korean troops stormed across the 38th parallel and invaded South Korea. The North Korean soldiers caught South Korea’s forces off guard and threw them into a hasty southern retreat. The United Nations quickly condemned the invasion and demanded an immediate cessation of hostilities and for North Korea to withdraw its armed forces to the 38th parallel. When the North Koreans failed to comply, the U.N. Security Council passed a resolution on June 27 recommending that its members provide military assistance to South Korea.
U.S. President Harry Truman (1884-1972) soon agreed to send American forces into action, and on July 7 the Security Council recommended that all U.N. forces sent to South Korea be put under U.S. command. The next day, General Douglas MacArthur was named commander of all U.N. forces in Korea.
By early August, the Allies had been pushed back to the Pusan Perimeter, a defensive line around an area in the southeastern corner of the Korean peninsula. However, throughout August and into September, the Americans and their counterparts fought off attacks from the North Koreans and prevented them from advancing any further.
Inchon Landing: September 15, 1950
Meanwhile, MacArthur, who had commanded the Allied forces in the Southwest Pacific during World War II, had been advocating for a plan to land troops behind the enemy lines at Inchon (now known as Incheon) and attack the North Koreans from both directions. MacArthur’s proposal met with resistance from other American military leaders, who pointed to a variety of challenges associated with landing at Inchon, including the narrow port channel and extreme tides. MacArthur argued that these factors would mean the North Koreans wouldn’t expect the Allies to attempt an amphibious landing there. At an August 23, 1950, conference of top U.S. military leaders at his headquarters in Tokyo, Japan, MacArthur stated, “The only alternative to a stroke such as I propose will be the continuation of the savage sacrifice we are making at Pusan, with no hope of relief in sight. Are you content to let our troops stay in that bloody perimeter like beef cattle in the slaughterhouse? Who will take the responsibility for such a tragedy? Certainly, I will not.”
MacArthur received the official go-ahead for the Inchon landing, codenamed Operation Chromite, and the port was captured by U.S. Marines on September 15, 1950. American-led U.N. troops then pushed inland to retake Seoul on September 26. Allied troops then converged on the North Korean army from the north and the south, killing or capturing thousands of enemy soldiers.
Korean War: The Fighting Continues
In October, American and South Korean troops advanced across the 38th parallel, and sent the North Koreans into retreat. Pyongyang, the North Korean capital, was captured on October 19. However, as the Americans moved north toward the Yalu River, the border between North Korea and Communist China, their advance was halted when China entered the fray that fall. In late November, a massive force of Chinese troops sent the Allies into retreat. In early January 1951, the Communists recaptured Seoul, only to have the Allies reoccupy it in March.
In April 1951, Truman removed MacArthur from his command after he publicly threatened to bomb China in defiance of Truman’s stated war policy. Truman feared that an escalation of fighting with China would draw the Soviet Union into the Korean War. MacArthur’s dismissal set off a brief uproar among the American public, but Truman remained committed to keeping the conflict in Korea a “limited war.”
Korean War: 1953 Armistice
By May 1951, the communists were pushed back to the 38th parallel, and the battle line remained in that vicinity for the rest of the war. On July 27, 1953, after two years of negotiation, military leaders from China, North Korea and the United Nations signed an armistice that ended the fighting and created a new boundary near the 38th parallel that gave South Korea some additional territory and established a 2.5-mile-wide demilitarized zone to serve as a buffer between the two Koreas. Because North Korea and South Korea never signed a permanent peace treaty, they are technically still at war today.
More than 500,000 American, South Korean and other U.N. troops were killed, captured or reported missing in the Korean War, while North Korean and Chinese military casualties have been estimated at nearly 1.6 million. By some estimates, civilian deaths were at least equal to the combined number of military casualties.