On June 25, 1950, the armed forces of the Democratic People's Republic of Korea (North Korea) crossed the 38th parallel, the line dividing Korea into two parts, and invaded the Republic of Korea (South Korea). The attack, aimed at reuniting the country under Communist rule from the North, sparked the Korean War. Two days later, the United Nations Security Council approved a resolution, introduced by the United States, asking member nations to assist South Korea. The resolution succeeded because the Soviet Union, North Korea's supporter, was absent and unable to veto, or reject, the measure.

Under the flag of the United Nations, 16 countries sent military forces to South Korea's defense, most coming from the United States. Many others contributed equipment, supplies, and other support. North Korea's main allies were the Soviet Union, which supplied it with arms, and China, which later sent many troops.

The war raged throughout the nation, causing great destruction and loss of life before an armistice was signed in 1953. Militarily, neither side officially won, but the aggression against South Korea had been repulsed and the right of states to be free from the threat or use of force had been preserved. For more information on the events leading up to the division of Korea, see the history sections of the articles Korea, North and Korea, South.

North Korean Offensive. Within the first two days of the war, the well-equipped and well-trained North Korean forces had already succeeded in pushing aside the outnumbered and poorly trained army of the Republic of Korea (ROK) and had captured Seoul, the capital of South Korea. Meanwhile, U.S. president Harry S. Truman had ordered the use of U.S. forces under General Douglas MacArthur, the Far East commander, in support of the South Koreans. On July 5 the first U.S. troops, part of the 24th Infantry Division, sent from Japan, engaged the North Koreans at Osan, south of Seoul. These efforts were intended to delay the North Koreans, who, by August 1950, had overrun all of the peninsula, except for an area around the southeastern port city of Pusan known as the Pusan perimeter. Here the North Korean offensive was stopped, as the U.S. 8th Army and ROK forces regrouped and received reinforcements.

United Nations Counterattack. From Pusan, MacArthur, who had been named to head the United Nations command, planned a daring counterattack. On September 15, an amphibious landing, combining naval, marine, and army forces, was launched against the North Korean-occupied port of Inchon, near Seoul, on South Korea's western coast. Although Inchon's difficult tides and currents made it a hazardous operation, it was a complete success. By late September, Seoul was recaptured. At the same time, the U.S. 8th Army had broken out of the Pusan perimeter and the North Koreans, caught in a two-pronged attack, were in retreat on all fronts. By October, they had fled back across the 38th parallel.

A decision to cross the dividing line into North Korea, to completely destroy its armies and unify the peninsula, was approved by the United Nations General Assembly on October 7. Advancing northward swiftly against little opposition, the United Nations forces took Pyongyang, the North Korean capital, on October 19. By November 21 they had reached the Yalu River, part of North Korea's boundary with Manchuria, a region of China. An early end to the war was expected.

China Enters the War. A warning by the Chinese Communist government that it would not allow the destruction of North Korea had been disregarded. Now, claiming that the United Nations advance threatened its borders, China completely changed the nature of the war. On November 25, massive numbers of Chinese troops attacked the United Nations lines. Caught by surprise and overwhelmed, the United Nations forces began a long retreat, which ended, in January 1951, with Seoul once more in Communist hands. From this low point, the United Nations troops slowly but stubbornly pushed northward again, retaking Seoul in March 1951.

MacArthur Dismissed. The Allied aims in the war had now shifted to maintaining South Korea's territorial boundaries and seeking an end to the fighting, avoiding the possibility of the war's expansion beyond Korea. MacArthur, who had urged the bombing of Chinese troop-staging areas inside the Manchurian border, publicly criticized these limited aims. This was in violation of President Truman's directive, and in April 1951, Truman dismissed MacArthur from command. He was replaced by Lieutenant General Matthew Ridgeway, commander of the U.S. 8th Army.

Stalemate and Peace Efforts. Between April and May 1951, some of the heaviest fighting of the war took place between Chinese and United Nations forces. A last Chinese offensive, in May, was repulsed with heavy casualties, and by June, both sides were entrenched along the 38th parallel, where the war had begun. A stalemate had developed, and the war became one of grinding, brutal fighting, as each side fought for a small advantage over the other.

The Soviet Union had proposed negotiations for a cease-fire at the United Nations on June 23, 1951. Representatives of the two sides first met at Kaesong on July 10. The talks, which continued at nearby Panmunjom, went on for two years, an armistice finally being signed on July 27, 1953. Military casualties on both sides exceeded 1.5 million. More than 54,000 Americans had died in action or from injuries and disease. Millions of Koreans had been killed, and many more had been left homeless or become refugees.


From Grolier's The New Book of Knowledge

Chong-Sik Lee
University of Pennsylvania
Author, The Politics of Korean Nationalism

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