War Breaks Out
Under the guise of a counter-attack, the North Korean Army struck in the pre-dawn hours of Sunday, June 25, 1950, crossing the 38th parallel behind a firestorm of artillery. The North claimed Republic of Korea Army (ROK) troops under the "bandit traitor Syngman Rhee" had crossed the border first, and that Rhee would be arrested and executed
Equipped with 594 Soviet made tanks, the North Koreans had 150 additional tanks in North Korea, the North Korean military began the war with about 357 aircraft, including several fighters and bombers, these aircraft were assigned to the invasion while 114 more planes were in North Korea. Their navy had several small warships, and launched attacks on the South Korean Navy. North Korea's most serious weakness was its lack of a reliable logistics system for moving supplies south as the army advanced, but the South Korean forces were weak and ill-equipped compared to the North Koreans. Thousands of Korean civilians running south were forced to hand-carry supplies, many of whom later died in North Korean air attacks. Other civilians died at the hands of the fleeing South Korean police and armed forces who staged mass executions of political prisoners.
The South Korean Army had 150,000 soldiers armed, trained, and equipped by the U.S. military, and as a force was deficient in armor and artillery. The South Korean military also had only 40 tanks, 14 attack planes, and few anti-tank weapons. There were no large foreign combat units in the country when the war began, but there were large American forces stationed in nearby Japan.
The North's well-planned attack with about 415,000 troops achieved surprise and quick successes. North Korea attacked a number of key places including Kaesŏng, Chuncheon, Uijeongbu and Ongjin.
Within days, South Korean forces, outnumbered, outgunned, and often of dubious loyalty to the southern regime, were in full retreat or defecting en masse to the North. As the ground attack continued, the North Korean Air Force conducted bombing of Kimpo Airport near Seoul. North Korean forces occupied Seoul on the afternoon of June 28.
However, North Korea's hope for a quick surrender by the Rhee government and the reunification of the peninsula evaporated when the United States and other foreign powers intervened with UN approval.
The invasion of South Korea came as a surprise to the United Nations. In the preceding week, Acheson had told the United States Congress on June 20 no such war was likely. Instead of pressing for a Congressional declaration of war, which he regarded as too alarmist and time-consuming when time was of the essence, Truman went to the United Nations for approval (though he ordered U.S. military forces to Korea before any resolution had been adopted).
The same day the war had officially begun (June 25), the United Nations immediately drafted UNSC Resolution 82, which called for:
1. all hostilities to end and North Korea to withdraw to the 38th Parallel;
2. a UN Commission on Korea to be formed to monitor the situation and report to the Security Council;
3. all UN members to support the United Nations in achieving this, and refrain from providing assistance to the North Korean authorities.
The resolution was unanimously passed in the Security Council thanks to the temporary Soviet absence from the Security Council — the Soviets were boycotting the Security Council, protesting that the Chinese seat should be transferred from the (Kuomintang-controlled) Republic of China to the Communist People's Republic. With the Soviets absent and unable to veto the resolution, and with only Yugoslavia abstaining, the UN voted to aid South Korea on June 27. The resolution led to direct action by the United States, whose forces were joined by troops and supplies from 15 other UN members: Canada, Australia, New Zealand, UK, France, South Africa, Turkey, Thailand, Greece, the Netherlands, Ethiopia, Colombia, the Philippines, Belgium and Luxembourg. However, the United States provided 50% of the ground forces (South Korea provided most of the remainder), 86% of the naval power, and 93% of the air power. Some historians have called the mission "a U.S. operation behind a blue international fig leaf."
The Soviet Union and its allies challenged the resolution on grounds of illegality since a permanent member of the council (the Soviet Union) was absent from the voting. Against this, the view prevailed that a permanent member of the Council had to explicitly veto a resolution in order to defeat it. The North Korean government also did not concur, arguing that the conflict was a civil war, and therefore not clearly within the scope of the UN. In 1950, a Soviet resolution calling for an end of hostilities and withdrawal of foreign troops was rejected.
American public opinion was solidly behind the intervention. However, Truman later took harsh criticism for not obtaining a declaration of war from Congress before sending troops to Korea. Thus, "Truman’s War" was said by some to have violated the spirit, and the letter, of the United States Constitution.
Despite the post-World War II demobilization of U.S. and allied forces, which caused serious supply problems for American troops in the region, the United States still had substantial forces in Japan to oppose the North Korean military. These American forces were under the command of General Douglas MacArthur. Apart from British Commonwealth units, no other nation could supply sizable manpower.
On being told of the outbreak of large-scale hostilities in Korea, Truman ordered MacArthur to transfer munitions to the ROK Army, while using air cover to protect the evacuation of U.S. citizens. Truman did not agree with his advisors, who called for unilateral U.S. air strikes against the North Korean forces, but did order the Seventh Fleet to protect Chiang Kai-Shek's Taiwan. The Nationalist government (confined to Taiwan) asked to participate in the war. Their request was denied by the Americans, who felt that it would only encourage PRC intervention.
The first significant foreign military intervention was the American Task Force Smith, part of the U.S. Army’s 24th Infantry Division based in Japan. On July 5, it fought for the first time at Osan and was defeated with heavy losses. The victorious North Korean forces advanced southwards, and the half-strength 24th Division was forced to retreat to Taejeon, which also fell to the Northern forces. General William F. Dean was taken prisoner.
By August, the South Korean forces and the U.S. Eighth Army under General Walton Walker had been driven back into a small area in the southeast corner of the Korean peninsula around the city of Pusan. As the North Koreans advanced, they rounded up and killed civil servants, a number of whom had earlier helped conduct campaigns to suppress domestic opposition to Rhee's regime and had been collaborators. On August 20, MacArthur sent a message warning Kim Il Sung that he would be held responsible for further atrocities committed against UN troops.
By September, only the area around Pusan — about 10 percent of the Korean peninsula — was still in coalition hands. With the aid of massive American supplies, air support, and additional reinforcements, the UN forces managed to stabilize a line along the Nakdong River. This desperate holding action became known in the United States as the Pusan Perimeter.
Escalation of the Korean war
In the face of fierce North Korean attacks, the allied defense became a desperate battle called the Battle of Pusan Perimeter by Americans. However, the North Koreans failed to capture Pusan.
American air power arrived in force, flying 40 sorties per day in ground support actions, targeting North Korean forces. Strategic bombers (mostly B-29s based in Japan) closed most rail and road traffic by day, and destroyed 32 critical bridges necessary for the conduct of warfare. Trains used by military and civilians alike waited out the daylight hours in tunnels.
Throughout all parts of Korea, the American bombers knocked out the main supply dumps and eliminated oil refineries and seaports that handled imports to starve North Korean forces of ammunition and other martial supplies. Naval air power also attacked transportation choke points. The North Korean forces were already strung out over the peninsula, and the destruction caused by American bombers prevented needed supplies from reaching North Korean forces in the south.
Meanwhile, supply bases in Japan were pouring weapons and soldiers into Pusan. American tank battalions were rushed in from San Francisco; by late August, America had over 500 medium tanks in the Pusan perimeter. By early September, UN-ROK forces were decidedly more powerful and outnumbered the North Koreans by 180,000 to 100,000. At that point, they began a counterattack. next