Korean War

V

North Korean Victories

During the summer of 1949, South Korea had expanded its army to about 90,000 troops, a strength the North matched in early 1950. The North had about 150 Soviet T-34 tanks and a small but effective air force of 70 fighters and 62 light bombers—weapons either left behind when Soviet troops evacuated Korea or bought from the USSR and China in 1949 and 1950. By June 1950 American data showed the two armies at about equal strength, with roughly equal numbers amassed along the 38th parallel. However, this data did not account for the superior battle experience of the North Korean army, especially among the troops who had returned from China.

The fighting began around 3 or 4 am on June 25 at the western end of the parallel. Initial intelligence reports were indeterminate as to who started the fighting, but by 5:30 am the formidable 6th Division of the (North) Korean People’s Army (KPA) had joined the fighting in the west. At roughly the same time, KPA forces in the center of the peninsula dealt a heavy blow to the ROK Army (ROKA) south of Cheorwon. The ROKA fell back and two KPA divisions and an armored brigade crashed through the 38th parallel, beginning a daunting march toward Seoul, which lay just 50 km (30 mi) to the south.

Just 20 km (12 mi) north of Seoul stood the town of Uijeongbu, a critical line of defense for the South maintained by an ROKA division. By the morning of June 26, the division at Uijeongbu had not committed its forces to battle, probably because it was waiting to be reinforced by another division from the interior of South Korea. However, when the reinforcing division finally arrived on June 26, troops panicked, mutinied, and fled. The reasons for the mutiny were many, including the relative lack of ROKA firepower, poor training, and ultimately the unpopularity of the Rhee government—which had nearly been voted out of office in relatively free elections held a month earlier. The collapse at Uijeongbu left a gaping hole in the South Korean defensive line, and North Korean troops poured through. The ROK government fled Seoul, which was taken on June 28 by a force of about 37,000 North Korean troops.

VI

U.S. Troops to Korea

The quick and virtually complete collapse of resistance in the South energized the United States to enter the war in force. Secretary of State Acheson dominated the decision making and soon committed American air and ground forces to the fight. Acheson successfully argued that the United States should increase military aid to the ROK and provide air cover for the evacuation of Americans from Korea. He also persuaded the president to place the Seventh Fleet of the U.S. Navy in the Taiwan Strait. This was needed, he argued, to prevent the Communist Chinese government on the mainland from invading the island of Taiwan, where the Nationalist Chinese government had retreated after the mainland fell to the Communists in 1949. The following day Acheson developed the fundamental strategy for committing American air and naval power to the Korean War, a strategy approved by Truman that evening but not yet approved by the United Nations, the Department of Defense, or the U.S. Congress.

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UN support for the defense of South Korea enabled Truman and Acheson to gain public support for U.S. intervention. Only two days after the invasion, on June 27, at the urging of the United States, the UN Security Council voted to repel the North Korean invasion. The USSR, which could have vetoed the vote, instead boycotted it. The USSR claimed its boycott was a response to the UN’s refusal to admit Communist China; however, historians have been unconvinced by this argument. On June 25 Stalin explicitly told the USSR’s UN representative not to return to the Security Council, but Stalin's reasons for this order are not known. Some historians speculate that Stalin either wanted to draw U.S. forces into a war that would drain the country of troops and money, or that he hoped to reveal the UN as an American tool.

American ground troops were finally committed in the early morning of June 30, over the reluctance of the Joint Chiefs of Staff (the United States’ top military officers). The Joint Chiefs were concerned about the limits of American power. In June 1950 the total armed strength of the U.S. Army was 593,167, with an additional 75,370 Marines. North Korea alone was capable of mobilizing perhaps 200,000 combat soldiers, in addition to the immense reserve of China’s People’s Liberation Army (PLA). Nonetheless, Truman and others were motivated by the news that the ROKA had mostly ceased to fight. Truman did not seek a declaration of war from the U.S. Congress, relying instead on the United Nations’ support.

In July, World War II hero General Douglas MacArthur was placed in command of U.S. troops in Korea. At first MacArthur wanted only a regimental combat team. Within a week, however, he cabled Washington that the KPA was “operating under excellent top level guidance and had demonstrated superior command of strategic and tactical principles.” He consequently asked for a minimum of 30,000 American combat soldiers in the form of four infantry divisions, three tank battalions, and assorted artillery.

VII

The Busan Perimeter

In the summer of 1950 the Korean People’s Army pushed southward with dramatic success, inflicting one humiliating defeat after another on the American forces. An army that had defeated Germany and Japan in World War II found itself overwhelmed by what many thought was a hastily assembled, ill-equipped peasant army said to be doing the bidding of a foreign imperial power. By the end of July 1950, the combined U.S. and ROK forces numbered 92,000 at the front (47,000 were Americans), compared with 70,000 KPA soldiers at the front. Nonetheless, the KPA advance continued until the North Korean forces occupied roughly 90 percent of South Korea. Kim Il Sung later said that his plan had been to win the war in a single month, and by the end of July he nearly had done so.

In the first week of August the U.S. 1st Marine Brigade arrived and finally stabilized the U.S. and ROK forces, which by that time guarded only a small area on the southeasternmost part of the peninsula. The right-angled front, known as the Busan Perimeter, stretched 80 km (50 mi) from Pohang on Yŏgil Gulf to Daegu in the interior before bending south 110 km (70 mi) to the coastal Jinju-Masan region. The port city of Busan lay behind the front on the peninsula’s southeastern tip.

The city of Daegu became a symbol of the American determination to halt the KPA's advance, and many attacks were repelled there. However, it was probably due to a tactical error at Pohang, on the northeastern perimeter, that the KPA failed to occupy Busan and unify the peninsula. The official American historian of the war, Roy Appleman, wrote that the 'major tactical mistake' of the North Koreans was not to press their advantage on the eastern coastal road between Pohang and Busan. The KPA division near Pohang was concerned about covering its flanks and so held its position. Had it instead moved quickly on Pohang and then combined with other KPA divisions, Appleman concluded that Busan in all likelihood would have fallen. In any event, the perimeter held for most of August.

At the end of August KPA forces launched their last major offensive at the perimeter, severely straining the American-Korean lines for the next two weeks. On August 28 three of the advancing KPA battalions succeeded in breaching the critical parts of the perimeter. The cities of Pohang and Jinju were both lost, with KPA forces advancing along both coasts to Busan. Another assault was being launched on the city of Daegu, with enough success that U.S. commanders evacuated the Eighth Army headquarters from Daegu to Busan. Prominent South Koreans began leaving Busan for the nearby Tsushima Islands of Japan. Only in mid-September did it become clear that the U.S. and ROK armies would stop the advance. The decisive factor was numbers. MacArthur succeeded in committing most of the battle-ready divisions in the entire American armed forces to the Korean fighting; by September 8 the 82nd Airborne Division was the only combat-trained Army unit not in Korea. Although many of these units were with the pending amphibious operation that would land at Incheon, near Seoul, some 83,000 American soldiers and another 57,000 South Korean and British troops faced the North Koreans at the Busan front. North Korean forces at the front, including guerrillas and a sizable number of female soldiers, numbered 98,000. The Americans had also accumulated five times as many tanks as the KPA and vastly superior artillery. They also had complete control of the air, which they had maintained since the early days of the war. The price for repelling the assault was steep casualties, totaling 20,000 Americans, with 4,280 dead, by September 15.

VIII

Invasion at Incheon

In mid-September 1950, MacArthur oversaw an amphibious landing at Incheon, a port 35 km (22 mi) west of Seoul. The harbor at Incheon had treacherous tides that could easily have grounded a flotilla of ships landing at the wrong time. Fortunately, Admiral Arthur Dewey Struble, the Navy's foremost expert on amphibious landings, commanded the flotilla. Struble had led the World War II landing at Leyte in the Philippines, and he had directed naval operations off Omaha Beach during the Normandy invasion in Europe. These World War II experiences served him well at Incheon, where he commanded an enormous fleet of 261 ships through the shifting bays and flats, depositing 80,000 Marines ashore with very few losses.

Although the Marines landed almost unopposed, they faced a deadly gauntlet before arriving at Seoul. By the end of September, however, U.S. forces had fought their way into Seoul and recaptured the capital. For years, many American historians held that the North Koreans were surprised by the invasion, but new evidence suggests that this was not the case. The North Koreans simply could not resist the assault and so began what North Korean historians have called euphemistically 'the great strategic retreat,' removing their troops from the South to guard their northern homeland.

Shortly after the Incheon landing, U.S. forces retrieved a document that contained Kim Il Sung’s thoughts on the fighting in the South. “The original plan was to end the war in a month,” he wrote, but “we could not stamp out four American divisions.” Instead of following orders to march promptly southward, the North Korean units that had captured Seoul dallied, thereby giving “a breathing spell” to the Americans. Kim wrote that from the beginning the North’s “primary enemy was the American soldiers,” but he acknowledged that “we were taken by surprise when United Nations troops and the American Air Force and Navy moved in.” This suggests that Kim anticipated the involvement of American ground forces, but not in such size, and not with air and naval units. Perhaps the North Koreans believed that Soviet air and naval power would either deter or confront their American counterparts. Or perhaps they simply believed, like the U.S. Joint Chiefs of Staff, that the vast majority of American battle-ready infantry would not be transferred from all over the globe to this small peninsula of seeming marginal importance to U.S. global strategy.

Regardless, by early October 1950 the North had been pushed from South Korea. The war for control of the South left 111,000 South Koreans killed, 106,000 wounded, and 57,000 missing; 314,000 homes had been destroyed, 244,000 damaged. American casualties totaled 6,954 dead, 13,659 wounded, and 3,877 missing in action. North Korean casualty figures are not known.

IX

The March North and China’s Entry

The U.S.-led forces might have reestablished the 38th parallel as the border between North and South Korea, ended the war, and declared that the Truman Doctrine’s policy of containing Communism had been achieved. Instead, MacArthur sent troops across the parallel into North Korea in early October. Historians later faulted MacArthur for taking this action without Truman’s approval, but evidence has since shown that Truman approved the march north at the end of August, even before the landing at Incheon. As the summer progressed, nearly all of Truman’s senior advisers decided the chance had come not only to contain Communism but to roll it back. Thus, National Security Council document 81 authorized MacArthur to 'roll back' the North Korean regime if there were no Soviet or Chinese threats to intervene. The document also instructed MacArthur to use only Korean troops near the Chinese border so as not to further antagonize China.

In September and October 1950 U.S. intelligence agencies generally concluded that China would not enter the war. On September 20 the Central Intelligence Agency (CIA) noted that there was a slight possibility that Chinese 'volunteers' might enter the fighting, and a month later it noted 'a number of reports' that units from Manchuria (along the Chinese border with Korea) might be sent to North Korea. Nonetheless, the CIA decided that 'the odds are that Communist China, like the USSR, will not openly intervene in North Korea.' MacArthur swept confidently onward. By October 19 UN troops had captured the North Korean capital, P’yŏngyang, lying 150 km (90 mi) northwest of the 38th parallel.

Three days earlier, Chinese troops had crossed their border at the Yalu River into North Korea. They dealt heavy losses to ROK troops and bloodied U.S. forces as well, then abruptly ceased offensives for three weeks. This incursion by China did not stop the American march to the Yalu. General Walter Bedell Smith, director of the CIA, wrote on November 1 that the Chinese 'probably genuinely fear an invasion of Manchuria.' He also predicted the Chinese would try to establish a buffer zone along the border for security 'regardless of the increased risk of general war.' However, the CIA still found insufficient evidence throughout November that China would mount a major offensive.

North Korean and Chinese documents released or declassified in the 1980s and 1990s tell a different story. China did not enter the war purely to protect its border. Rather, Mao decided early in the war that should the North Koreans falter, China had an obligation to help them because many North Koreans had sacrificed their lives alongside Chinese—in the Chinese revolution that overthrew the imperial government in 1911 to 1912, in resistance to Japan’s decades of occupation, and in the Chinese civil war of 1946 to 1949. On August 4, 1950, Mao told the Chinese Politburo (the highest decision-making body of the Chinese Communist Party) that he intended to send troops to Korea 'in the name of a volunteer army' should the Americans reverse the tide of battle. The day after UN troops crossed the 38th parallel, Mao informed Stalin of his decision to invade. In other words, it was not the approach of American troops on the Chinese border that prompted China’s attack; it was the American strategy to roll back North Korean Communism.

The North Koreans and Chinese apparently waited to attack UN forces until they were well inside North Korea in order to stretch the UN supply lines and gain time for a dramatic reversal on the battlefield. On November 24 MacArthur launched a general offensive all along the northern front, which was nearing the Yalu. He described it as a 'massive compression and envelopment,' a pincer movement to trap the remaining KPA forces that were backed into the mountainous northern part of the peninsula. The offensive rolled forward for three days against little or no resistance, with ROK units succeeding in entering the important city of Ch’ŏngjin on the upper east coast, 70 km (45 mi) short of China. Lost amid the victory were reports from U.S. reconnaissance pilots that long columns of enemy troops were 'swarming all over the countryside.'

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