At the close of World War II it was agreed that the Soviet Union would accept the surrender of Japanese troops in the northern part of Korea, and the United States, the surrender of those to the south. For this purpose, the 38th parallel of north latitude was designated as the line dividing the areas of responsibility.
In a short time the USSR established a puppet Communist government in the sector under Russian control, organized an army of Koreans, and militarized the line of the 38th parallel. A United Nations commission, established to conduct national elections in Korea, was denied access to northern Korea. Nevertheless, the Republic of Korea was proclaimed in southern Korea on Aug. 15, 1948, and Syngman Rhee was chosen president in free elections. On September 9 the formation of the Democratic People's Republic was announced in the north, with claim to authority over all of Korea. Thus the 38th parallel, "a fortuitous line resulting from the exigencies of war", had become a political frontier.
True to the philosophy of their Communist mentors, the North Koreans lashed their brethren to the south with "cold war" tactics - propaganda, subversion, terrorism, and border "incidents." In December 1948, the Soviet Union announced that its troops had evacuated North Korea, but verification by the United Nations commission was not permitted. The last United States troops withdrew in June 1949, but a small military advisory group was left behind at the request of the new government of South Korea.
Korean Armed Forces
By June 25, 1950 - when open hostilities began - the Russians and Chinese Communists had built the North Korean Army and Air Force into effective fighting units. The army numbered some 127,000, leavened with many battle-hardened Koreans who had served with the Chinese Communists in their conquest of China proper. In addition, there was a Border Constabulary (19,000 men) composed of the most fanatical North Korean converts to communism. The army was well equipped with Russian artillery, light weapons, and about 150 tanks, and it had been trained well by Russian instructors. The air force had some 200 Russian-built planes, about half of which were of fighting types; no naval forces of consequence were formed.
The South Korean Army numbered approximately 98,000, organized into eight divisions. Four of these were equipped with American light weapons and light artillery, but they lacked tanks, antitank weapons, and heavy artillery; the other four divisions had light weapons only, mostly of old Japanese stocks. No combat aircraft were available, and there were only a few small naval vessels.
Invasion of South Korea
The Korean Peninsula is, in effect, a continuous mountain range, with many spurs. There are few travers-able routes for sizable armed forces running south from North Korea. The best of these roads leads to Seoul, the South Korean capital. On June 25, 1950 (Korean time)1, on the pretext of repelling an invasion by the South Koreans, the North Koreans struck for Seoul. Caught by surprise, and with their forces dispersed, the South Koreans could offer little effective resistance.
Acting swiftly after the report of fighting, the U.N. Security Council adopted a United States resolution branding the invasion as a breach of the peace and calling for immediate cessation of hostilities. On June 27, in another United States resolution, the Security Council recommended that member states of the United Nations "furnish such assistance to the Republic of Korea as may be necessary to repel the armed attack. ..." (Soviet delegates, on temporary boycott of the United Nations, were not present to veto the proposals.) That same day President Harry S. Truman authorized the use of air and naval forces to support the South Koreans, and on June 30 he expanded this assistance to include American ground forces.
By July 8, a United Nations Command, under Gen. Douglas MacArthur, was operating in Korea. An American ground force detachment, flown in from Japan, made a stand at Osan on July 5 to block an advance south from Seoul. It was overwhelmed and forced to withdraw. Successive stands by troops rushed forward were equally unsuccessful. By August 5, the U.N. Command was pinned behind the Naktong River, defending a perimeter around the port of Pusan, through which the command was being built up and supplied. Repeated attacks on this "Pusan perimeter" made only minor gains, primarily because they were not concentrated or coordinated, and they lacked strength in depth. By rapid shifting of troops within the perimeter to meet each threat as it arose, the American Eighth Army (commanded by Lt. Gen. Walton H. Walker) succeeded in preventing a major breakthrough.
United Nations Counteroffensive
Meanwhile, MacArthur had been gathering troops in Japan for a counteroffensive. Most of the North Korean Army was deployed around the Pusan perimeter, and its supply line ran back through Seoul. On September 15, 1950, the United States Navy, in a brilliant amphibious operation involving many hazards, landed the marines and soldiers of the American 10th Army Corps (commanded by Major General Edward M. Almond) at Inchon, a port southwest of Seoul. Simultaneously, the Eighth Army launched an offensive from within the Pusan perimeter. Assailed from front and rear, and with their communications pulverized by United Nations air and sea power, the North Korean Army disintegrated. Most of the troops escaped into the rugged mountains; many doffed their uniforms and melted into the populace. After reorganizing, the United Nations forces moved northward on a broad front. By Oct. 26, 1950, advance elements had reached the Yalu River at Chosan, and more than 100,000 North Koreans had been captured.
Chinese Communist Intervention
During the last days of October 1950, several United Nations units reported contact with Chinese Communist forces. In fact, by then some 300,000 Chinese "volunteers" had been secretly assembled in North Korea, and more than 1,000,000 rested in reserve behind the Yalu. Not believing that Communist China would actually intervene, Mac-Arthur ordered a continuation of the advance to the Yalu, though exposed advance elements on the western sector were called back. On November 25 (after the United Nations Command had reached the November 24 line shown in map), the Chinese struck in strength. The Eighth Army, on the left, was forced to withdraw; by December 15 it had occupied a strong defensive position, generally along the 38th parallel. The 10th Corps, suddenly faced with isolation and destruction, particularly in the vicinity of the Changjin Reservoir, withdrew in bitter fighting to Hungnam on the east coast and was evacuated by sea to Pusan in the south.
On January 1, 1951, after regrouping, the Chinese Communists hurled 500,000 men against the Eighth Army position at the 38th parallel. (General Walker had been killed in an automobile accident on December 23, and Lt. General Matthew B. Ridgway now commanded the Eighth Army.) With callous indifference to losses, successive Communist waves struck the United Nations forces (then 365,000 men), eventually forced a withdrawal, and occupied Seoul on January 4. The Chinese offensive finally died out on Jan. 24, 1951 (along the line shown in map) due to logistical difficulties brought on primarily by persistent attacks on communications by United Nations air forces.
Taking advantage of the weakened condition of the Chinese, Ridgway launched a counter-offensive on January 25, while air and naval forces pounded enemy supply lines and centers.
By April 23, the United Nations forces had advanced to a strong position 20 miles north of the 38th parallel. On that day, the Chinese launched a violent offensive which threw the United Nations troops back across the parallel again. Early in May, however, the Chinese drive came to a halt, because of exhaustion, heavy casualties, and supply difficulties. Immediately, the United Nations troops counterattacked, driving the disorganized enemy northward, until by June 15, 1951, the advance was halted. During these seesaw operations United Nations casualties were heavy, but Chinese losses were appalling.
Forbidden to attack Chinese troops and supply installations in their sanctuary behind the Yalu - for fear of bringing on a general war - the United Nations Command had adopted a strategy of attrition and, with superior artillery, air, and naval forces, had striven to inflict the greatest possible casualties. Meanwhile, the Soviet Union sought to build up the Chinese Communist strength with supplies and large numbers of aircraft and weapons. (On April 11, 1951, in a dispute over extension of the war beyond the Yalu, President Truman relieved MacArthur and appointed Ridgway to over-all command. Lieutenant General James A. Van Fleet replaced Ridgway as commander of the Eighth Army.)
Period of the Armistice Talks
On June 23, 1951 a Soviet spokesman proposed that ceasefire discussions be undertaken; accordingly, on July 10 representatives of both sides met at Kaesong. These discussions soon broke down, but were resumed at Panmunjom on October 25. The negotiations, which dragged on over two long years, were marked by frequent suspensions and bitter discord, centering mainly on the questions of the military demarcation line, the repatriation of prisoners, and the composition of the Neutral Nations Supervisory Commission, whose task would be to enforce the provisions of an armistice. Finally a truce was agreed upon, and fighting ceased on July 27, 1953 (July 26, United States time).
During the talks, the line remained generally as it stood on June 15, 1951, but many bloody and costly fights took place to gain local advantages. Most important - and most bitterly contested - were the commanding terrain features known as the "Iron Triangle" and the "Punchbowl". Meanwhile, General Mark W. Clark had replaced Ridgway as supreme commander in May 1952, and in February 1953 Lt. General Maxwell D. Taylor had succeeded Van Fleet at the head of the Eighth Army. In the years following the armistice, the two sides faced each other in uneasy truce along the former battle line. The South Korean Army, which fought well during the war after its initial setback, assumed increasing responsibility in defense of the front. North Korea was converted into a military citadel.
United Nations Forces
In this, its first military action, the United Nations performed splendidly despite the many handicaps. (The provision of food alone was a major logistical problem because of national preferences and religious bans.) All contingents fought bravely and with dedication. The preponderance of military strength was provided by the United States (with ground, air, and naval forces) and the Republic of Korea. Great Britain provided two infantry brigades and Canada, one; in addition, both sent artillery and armor. Turkey also provided an infantry brigade, and lesser ground units were sent by Thailand, the Philippines, New Zealand, Australia, France, Greece, the Netherlands, Colombia, Belgium, Ethiopia, and Luxembourg. Naval units were furnished by Great Britain, Australia, Canada, Colombia, France, New Zealand, the Netherlands, and Thailand. Air units came from Australia, Canada, Greece, Thailand, and the Union of South Africa. Denmark, Italy, India, Norway, and Sweden provided medical units.
In this war, long called a "police action", the United Nations forces suffered casualties totaling about 74,000 killed, 250,000 wounded, and 83,000 missing and captured. The number of civilians killed was estimated at 400,000. United States losses, according to a final report issued by the Defense Department in November 1954, amounted to 33,629 killed or dead of wounds, 103,284 wounded, and 4,753 missing and presumed dead. Communist casualties (killed and wounded) were estimated at 900,000 Chinese and 520,000 North Koreans.