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The Korean War

History Page Type:
Friday, August 24, 2018
American Soldiers in the Korean War

The Korean War was a three-year struggle with ongoing political, social, and economic ramifications. From 1950 to 1953, the small Korean peninsula became the stage for one of the largest Cold War proxy wars. China and North Korea, aided by the Soviet Union, fought against the United States, South Korea, and an array of other countries acting under the authority of the United Nations. When it was finished, Korea lay split in two. Millions of soldiers and civilians perished in one of the bloodiest conflicts of the 20th century and international relations continued to deteriorate between communist and capitalist ideologies following the conclusion of the war.


Outside of a brief period of Korean independence from 1897-1910, Korea was heavily influenced or totally dominated by outside empires and nations, most prominently China and Japan, from 1600 to 1945. Following the Russo-Japanese War, Japan annexed the region as a protectorate. Communist and nationalist leaders fought against the rule of Japan for the entirety of World War II, finally gaining limited independence at the conclusion of the war.

Following the Yalta Conference in February of 1945, the Soviet Union guaranteed the Allies it would commence hostilities with Japan with three months of victory over Nazi Germany. The Soviets declared war on Japan August 9, 1945, three days following the U.S. use of the “Little Boy” atomic bomb on Hiroshima. Soviet forces stormed into Korea the next day and occupied the northern end of Korea to the 38th parallel, the line of demarcation decided upon in General Order No. 1, the document which formally acknowledged Japanese surrender. The two powers wanted to hold Korea under a joint trusteeship for five years but quickly realized such an arrangement was untenable. Two governments, one in the north and one in the south, were selected through biased elections. Kim Il-sung took power in the north, while Syngman Rhee controlled the south. Relations between North and South Korea deteriorated rapidly following the withdrawal of Soviet and American forces in 1948 and 1949, respectively.


The War Begins

In early 1950, General Secretary of the Soviet Union Joseph Stalin conceded to the wishes of Kim Il-sung, and vowed to secretly support an invasion of the south. Stalin stipulated that Chinese forces were to reinforce North Korean ones directly, as any direct Soviet intervention into the area could draw the United States into the war. The Chinese assented to this arrangement, as they needed funding from the Soviet Union to keep their economy from total ruin.

On June 25, 1950, North Korean forces — the Korean People’s Army (KPA) — assaulted the entirety of the 38th parallel. Armed with Soviet artillery and tanks, the KPA routed the South Korean forces, the Republic of Korea Army (ROK). Chaos ensued, and within a matter of days, the ROK had lost nearly 75% of their forces from death, capture, or mutiny. The KPA captured the South Korean capital, Seoul, and continued to march south, nearly occupying the entire peninsula. Even following the first American intervention on July 5, at the Battle of Osan, the KPA continued its push south against undermanned and undersupplied American, ROK, and U.N. forces.

Defense of Pusan, Inchon, and Chinese Intervention

By late July, the situation in South Korea was dire. The joint forces of the U.S., ROK, and U.N. were trapped into a 140-mile defensive line in the southeast corner of South Korea that contained the strategic port town of Pusan. After holding the line successfully against KPA probes, U.N. forces under the command of General Walton Walker launched a counteroffensive. The fighting was some of the most intense of the war, with the two sides going back and forth over the course of two weeks with little ground gained or lost.

The U.N. invasion of Inchon changed the course of the Korean War and prevented a swift victory by North Korea. In an effort to relieve pressure around the stagnated Pusan Perimeter, combined American, Canadian, French, English and South Korean forces easily captured Inchon using an amphibious-air attack miles behind the KPA’s front line. The conflict was now a two-front war. After U.N. forces retook Seoul, North Korean forces were essentially cut off from supplies and reinforcements, causing them to abandon their attacks on Pusan and retreat northward. A total collapse of the North Korean line resulted, and they were routed for several weeks back into North Korean territory. Military historian Spencer C. Tucker claimed the Inchon Maneuver was one of the most successful military operations conducted in modern warfare.[1] From the mid-September landing at Inchon to October 30, combined U.N. forces moved steadily northward, reaching the Chinese border by November of 1950.

China watched the conflict in Korea with growing concern. Both China and the Soviet Union supported the struggle of their North Korean allies politically and monetarily, but both initially considered direct intervention in the conflict as too dangerous. This sentiment changed in China following Inchon, when it appeared the U.N. forces would continue, virtually unimpeded, to the Chinese border. With the knowledge that some U.S. military leaders, chief among them General Douglas MacArthur, Commander of U.S. forces in Korea at the time, wanted to escalate the fight to defeat Communism in Asia once and for all, China was put in the difficult position of deciding if intervention in Korea was necessary.

Following several weeks of correspondence between Chinese leaders Mao Zedong (Chairman of the Communist Party), and Zhou Enlai (premier) with Soviet leaders Stalin, First Deputy Chairman Vyacheslav Molotov, and Deputy Chairman Lavrentiy Beria, the two parties agreed to direct military intervention by China. Over a three-week period, 200,000 Chinese troops secretly began marching from Manchuria, near the North Korean border, across the Yalu River and into North Korea itself. The First Phase Offensive of the Chinese military plan began, and U.N. troops engaged the Chinese forces head-on.

The First Phase was extremely successful, as U.N. and United States troops were caught entirely off guard. American troops were beaten back at the Battle of Unsan. The initial Chinese breakout in early November of 1950 saw their forces capture a large swath of northwestern North Korea. However, after their attacks, the Chinese retreated back into the mountains and allowed joint U.N. forces to retake ground. Chinese forces knew they stood a better chance by fighting a disjointed, guerrilla-style campaign rather than fighting head-on. By December 1, 1950, the U.N. and U.S. had actually gained more territory in the northeast than they had lost in the northwest. Russia still refused to provide men on the ground, but had agreed with Mao to provide air support (theoretically only within Chinese borders, though there were reports that Soviet fighters engaged in combat over North Korean airspace) and increased financial aid. Several more offensives were undertaken by the Chinese and North Korean forces. The offensives forced U.N. and U.S. troops back into South Korea, until they eventually repelled the advance in June of 1951.


Wide swaths of territory were gained and lost by both sides in the first year of the war, forcing both to nearly capitulate at different times. After June 14, 1951, no territorial changes occurred between the warring factions. By the time stalemate was reached in June, thousands of lives had been lost, and the line of demarcation between North and South Korea remained virtually the same as it had been before the outbreak of war.

Smaller military engagements occurred sporadically over the next two years. The U.N. conducted a massive bombing campaign when it became apparent that the lines of battle had stagnated. The resulting casualties were staggering, as thousands of Chinese and North Korean soldiers, as well as close to one million North Korean citizens, died in the bombings. More tonnage of explosive, incendiary, and napalm bombs were dropped in North Korea than throughout the entirety of the Pacific Theater during World War II. Some estimates claim that 85% of major structures in the entire nation were damaged or destroyed.

Intense talks between Chinese, North Korean, South Korean, U.N. and American leadership finally brought the war to an end in 1953. The Korean Armistice Agreement, signed on July 27, 1953, formally separated North and South Korea into individual, sovereign nations, and created a demilitarized zone (DMZ) that roughly followed the 38th parallel.

The Threat of Nuclear War

A well-known, but historically contentious, debate during and immediately after the Korean War was the United States’ willingness to use atomic weapons against North Korea (and possibly China as well). The Korean War began a mere five years following the conclusion of World War II. The memories of Hiroshima and Nagasaki were fresh in the minds of people across the globe. Furthermore, the Soviet Union successfully detonated their own atomic device in August of 1949.

Although the Soviet Union never entered the Korean War directly, leadership in Washington was understandably cautious of using atomic threats so close to Soviet borders. While Soviet atomic capabilities were still extremely limited compared to American ones, an atomic strike would almost certainly start off a chain of events which could impact Asia, Europe, and possibly Africa.

However, American leaders, such as President Truman and General Douglas MacArthur continued to posit that the option was indeed on the table. In an interview in November of 1950, Truman made the mistake of saying that the issue of whether to use atomic weapons was up to the military to decide; the Atomic Energy Act of 1946 explicitly stated that atomic firepower would be controlled by civilian authorities. By April of 1951, Truman had transferred nine Mark 9 nuclear warheads for military control, despite the concerns of Gordon Dean, the chairman of the Atomic Energy Commission. Dean questioned whether or not MacArthur would be responsible with the weapons and feared he might preemptively use them against targets in China.

An atomic attack never materialized. Conflicting narratives have emerged regarding the nature of American atomic strategy in Korea. How seriously American leadership considered using nuclear weapons during the war — especially in a potential attack on China rather than in a defensive effort on the Korean peninsula — is a topic of debate. Real steps were taken to ensure that such an option was available. Operation Hudson Harbor, which started in October of 1951, was a series of “dummy” runs into North Korea that replicated what a nuclear attack would look like. The goal was to show that American nuclear bombing tactics could be used in the conflict and thereby deter Soviet entrance into the war.

Some historians have hypothesized that General MacArthur was relieved from command in April of 1951 because of his insistence on provoking China. There was some credibility for the claim; MacArthur, in 1950, submitted a list of targets to be targeted with nuclear weapons in the case of a catastrophic collapse in Korea, with many targets located in China. Later, in 1954, MacArthur said he would have “dropped between 30 and 50 atomic bombs on air bases and other depots strung across the neck of Manchuria.” However, MacArthur later claimed this was not the case. Regardless, the tension between MacArthur and Truman led to a total breakdown in their relationship, causing Truman to replace MacArthur with General Matthew Ridgeway.

The decision to remove MacArthur was extremely unpopular with the American public, and Truman’s approval rating plummeted to a historically low twenty-three percent (lower than President Nixon during Watergate or President Johnson during the Vietnam War).[2] Truman did not run for reelection in 1952, possibly allowing Dwight Eisenhower to win against the weaker Democratic candidate Adlai Stevenson. Eisenhower ramped up threats of nuclear retaliation against China during both his presidential campaign and his first year in office, which some historians have speculated forced China to the negotiation table in Korea.[3] The perceived success of such a hardline strategy prompted further threats by American leaders throughout the 1950s and 1960s.


Estimates vary, but likely around four million people died during the Korean War, half of them civilians. General Curtis LeMay believed that by the end of the war, approximately 20% of the population of North Korea was dead. A majority of all industrial and residential buildings in North Korea were partially or completely destroyed. South Korean communities fared slightly better, but needed to undergo significant and costly rebuilding.

In the decade and a half following the war, both countries experienced tremendous economic hardship, forcing their allies to suspend debts and send aid. The South Korean economy eventually rebounded and boomed, becoming a top-15 economy in GNP by 2017. Conversely, North Korea has remained extremely impoverished under a largely agrarian and military society. Thousands perished in labor camps under the increasingly repressive Kim Il-sung and, later, his son and grandson, Kim Jong-Il and Kim Jong-un. In the 1990s, North Korea experienced a massive famine, killing an additional 200,000-450,000 people. By 2017, the North Korean economy still ranked outside the top-100 in GNP and the country was ranked last out of 167 nations surveyed by the Democracy Index, an index that measures a country’s state of democracy using several indicators such as political participation, civil liberties, and electoral processes.

Perhaps the most important part of the Korean War’s legacy for long-term international affairs was its impact on the Cold War. American foreign policy and domestic opinion was heavily influenced by the war. Although American and Sino-Soviet relations were not exactly cordial before the war, they became increasingly hostile during and after the conflict. American defense spending jumped dramatically during the conflict and remained high relative to historic norms for the next forty years, with anywhere between 5-17% of GDP going to the defense budget. The United States also formally backed Chiang Kai-shek’s breakaway government in Taiwan, a decision which still has ramifications to this day.

 Just years after World War II, the world had seen yet another large-scale war involving major powers. The Korean War proved once again that major conflicts, or the threat of their occurrence, would become a major factor in 20th-century politics. For the following forty years, the United States, China, and the Soviet Union jostled for dominance militarily, economically, and ideologically, bringing the world to the brink of war numerous times. The tactics used in this fight for power were initially tried and tested in Korea.


[1] Spencer C. Tucker, ed. Stanley Sandler, The Korean War: An Encyclopedia (Abingdon, U.K.: Routledge, 1996), 145.

[2] Michael D. Pearlman, Truman and MacArthur: Policy, Politics, and the Hunger for Honor and Renown (Bloomington, Indiana: Indiana University Press, 2008), 246, 326.

[3] Rosemary J. Foot, “Nuclear Coercion and the Ending of the Korean Conflict,” International Security (Winter 1988): 111-12.