Introduction to the Korean War (1950–1953)

When World War II ended, Korea was one of several nations artificially divided and occupied by members of the victorious Allied coalition. The 38th parallel was set as the line of demarcation separating the northern and southern halves of the peninsula. After the war, North Korea, which Japan had controlled for many years, was occupied by Soviet and American forces. The Soviets organized a Communist regime in 1948, chose longtime Communist Kim Il-sung as its first premier, and named the region north of the 38th parallel the Democratic People’s Republic of Korea. Korean nationalist Syngman Rhee won a United Nations–sponsored election that same year and became president of the Republic of Korea, also known as South Korea.

Fighting along the 38th parallel kept the divided country in a constant state of crisis. Despite the continuous violence, American forces withdrew in June 1949. The South Korean army was small, ill-trained, and poorly equipped—a sharp contrast to their Soviet-backed adversary to the north.

On June 25, 1950, North Korean forces invaded South Korea without warning. Within thirty-six hours, North Korean tanks had moved into Seoul, the South Korean capital. The United States reacted quickly and with great determination. On June 27, President Harry Truman committed United States ground forces stationed in Japan as well as air and naval forces to the fight. The American forces were inadequate to stem the powerful North Korean advance. By the end of the month, more than half the South Korean army had been destroyed. By early August, American and South Korean forces had been pushed as far as Pusan, a port city located on the southeastern tip of the peninsula. After violent fighting, a defense perimeter was established around the critical port and a stable boundary was assured.

American General Douglas MacArthur, commander of the UN forces, conceived a brilliant amphibious landing at Inchon, the west coast port located a few miles from Seoul. Within an hour and a half of the start of the assault, the critical island of Wolmi Do was captured. On September 29, after two weeks of fighting, Seoul was returned to the South Korean government. On October 1, UN forces chased the North Koreans past the 38th parallel.

The single most important decision of the war came next. Public demands for a complete victory supported MacArthur’s desire to pursuing the defeated foe across the demarcation line. The first crossings into North Korea took place on October 1, and China responded by sending “volunteers” to assist North Korea. By early December, UN forces found themselves in a desperate retreat southward. Throughout the rest of the winter and early spring, the lines fluctuated from south of Seoul to north of the 38th parallel. When a stalemate was finally reached in July 1951, the war had settled into trench warfare. The stalemate was a source of mounting frustration in the United States, influencing both the rise of McCarthyism and the presidential election of Dwight D. Eisenhower. A final armistice agreement was signed on July 27, 1953.