The Outbreak of the Korean War

35.3.3: The Outbreak of the Korean War

With the approval and support of Stalin and Mao Zedong and Kim Il-sung believing that the effort to unite the Korean Peninsula would be supported by much of the South Korean populations, North Korea invaded South Korea on June 25, 1950, marking the outbreak of the Korean War.

Learning Objective

Detail the events that led to the outbreak of war on the Korean Peninsula

Key Points

  • Following the 1948 elections under the auspices of the UN, the new South Korean government promulgated a new constitution and elected Syngman Rhee as president. While in the North the Soviet Union established a communist government led by Kim Il-sung, President Rhee’s regime excluded communists and leftists from southern politics. While Rhee aimed to eradicate communist and leftist groups, the anti-communist slogans were also applied to eradicate all his actual and alleged political opponents and establish authoritarian rule by inciting fear among civilians with no ties to communism.
  • In April 1948, what began as a demonstration commemorating Korean resistance to Japanese rule ended with the Jeju uprising, an attempted insurgency against the scheduled election on the Korean province of Jeju Island, followed by a brutal anticommunist suppression campaign. By early 1950, Rhee had about 20,000-30,000 alleged communists in jails and about 300,000 suspected sympathizers enrolled in the Bodo League.
  • Kim Il-sung believed that communist guerrillas had weakened the South Korean military and that a North Korean invasion would be welcomed by much of the South Korean population. Kim began seeking Stalin’s support but with Chinese Communist forces still engaged in the Chinese Civil War and American forces stationing in South Korea, Stalin did not want the Soviet Union to become embroiled in a war with the United States.
  • By spring 1950, the strategic situation changed. The Soviets had detonated their first nuclear bomb, American soldiers had fully withdrawn from Korea, and the Chinese Communists had established the People’s Republic of China. In April 1950, Stalin gave Kim permission to invade the South under the condition that Mao Zedong, the leader of China, would agree to send reinforcements if needed. Stalin made it clear that Soviet forces would not openly engage in combat to avoid a direct war with the Americans.
  • On June 25, 1950, the Korean People’s Army crossed the 38th parallel behind artillery fire. The KPA justified its assault with the claim that ROK troops had attacked first, and that they were aiming to arrest and execute the “bandit traitor Syngman Rhee.” There were initial South Korean claims that they had captured the city of Haeju, and this sequence of events has led some scholars to argue that the South Koreans actually fired first. Within an hour, North Korean forces attacked all along the 38th parallel.
  • In five days, the South Korean forces, which had 95,000 men on June 25, were down to less than 22,000 men. In early July, when U.S. forces arrived after the UN passed Resolutions 82 and 83 and it became clear the Soviets would not directly engage in the conflict, what was left of the South Korean forces was placed under U.S. operational command of the United Nations Command.

Key Terms

Bodo League
An official “re-education” movement whose members were communists, communist sympathizers, or actual and alleged political opponents of the President of South Korea Syngman Rhee. The members of the movement were forced into the membership and many were civilians with no ties to communism or politics.
Jeju uprising
An attempted insurgency on the Korean province of Jeju Island followed by a brutal anticommunist suppression campaign that lasted from April 3, 1948, until May 1949. The main cause for the rebellion was elections scheduled for May 10, 1948, designed by the UN to create a new government for all of Korea but only planned for the south of the country. Fearing this would further reinforce division, guerrilla fighters for the South Korean Labor party reacted violently, attacking local police and rightist youth groups stationed on Jeju Island.
war of attrition
A military strategy in which a belligerent attempts to win a war by wearing down the enemy to the point of collapse through continuous losses in personnel and material. This type of war is usually won by the side with greater resources.

 

 

“Anti-Communist” Purge in South Korea

Following the post-World War II division of Korea between the U.S. and the Soviet sphere of influence, the U.S. government cited the inability of the Soviet-U.S. Joint Commission to make progress and decided to hold an election under United Nations auspices with the aim of creating an independent Korea. The Soviet authorities and the Korean Communists refused to cooperate on the grounds it would not be fair. Many South Korean politicians also boycotted the idea. A general election was held in the South in 1948, marred by political violence and sabotage resulting in 600 deaths. North Korea held parliamentary elections three months later.

South Korean citizens protest Allied trusteeship in December 1945, author unknown.

South Korean citizens protest Allied trusteeship in December 1945, author unknown. Koreans on both sides of the 38th parallel refused to accept the imposed division of their country.

In 1948, the resultant South Korean government promulgated a new constitution and elected Syngman Rhee as President. The Republic of Korea (South Korea) was established on August 15, 1948. While in the North the Soviet Union established a communist government led by Kim Il-sung, President Rhee’s regime excluded communists and leftists from southern politics. Disenfranchised, they headed for the hills to prepare for guerrilla war against the US-sponsored ROK government. While Rhee indeed aimed to eradicate communist and leftist groups, the anti-communist slogans were applied to eradicate all his actual and alleged political opponents and establish the authoritarian rule by inciting fear among the civilians with no ties to communism or politics.

In April 1948, what began as a demonstration commemorating Korean resistance to Japanese rule ended with the Jeju uprising, an attempted insurgency against the scheduled election on the Korean province of Jeju Island, followed by a brutal anticommunist suppression campaign that lasted until May 1949. Although atrocities were committed by both sides, the methods used by the South Korean government to suppress the rebels were especially cruel, including random executions of women and children. In the end, between 14,000 and 30,000 people died as a result of the rebellion, or up to 10% of the island’s population. Some 40,000 others fled to Japan to escape the fighting. The persecution of actual and alleged communists in South Korea continued in the aftermath of the uprising. In December 1949, South Korean forces killed 86 to 88 people in the Mungyeong massacre. The victims were massacred because they were suspected communist supporters or collaborators (though some sources say nearly one-third of the victims were children) but the government blamed the crime on marauding communist bands. By early 1950, Syngman Rhee had about 20,000-30,000 alleged communists in jails and about 300,000 suspected sympathizers enrolled in the Bodo League re-education movement. The Bodo League gathered suspected communist sympathizers or Rhee’s political opponents but to fulfill the enrollment quota, many civilians with no ties to communists or politics were forced to become members.

Jeju residents awaiting execution in May 1948, author unknown.

Jeju residents awaiting execution in May 1948, author unknown. Jeju residents began protesting the UN-designed 1948 elections in the South a whole year before they took place. An attempt by the military government to disperse the crowds only brought more citizens of Jeju out in support of the demonstrations. The persecution of communists and leftists in South Korea and the refusal to accept the 1948 elections and the divide of the Peninsula were important factors behind the invasion of North Korea in 1950.

Political Situation Before the War

By 1949, South Korean forces had reduced the active number of communist guerrillas in the South from 5,000 to 1,000. However, Kim Il-sung believed that the guerrillas had weakened the South Korean military and that a North Korean invasion would be welcomed by much of the South Korean population. Kim began seeking Stalin’s support for an invasion in March 1949, but with Chinese Communist forces still engaged in the Chinese Civil War and American forces stationed in South Korea, Stalin did not want the Soviet Union to become embroiled in a war with the United States. By spring 1950, the strategic situation changed. The Soviets had detonated their first nuclear bomb in September 1949, American soldiers had fully withdrawn from Korea, and the Chinese Communists had established the People’s Republic of China. The Soviets had also cracked the codes used by the U.S. to communicate with the U.S. embassy in Moscow, and reading the dispatches convinced Stalin that Korea would not warrant a nuclear confrontation.

In April 1950, Stalin gave Kim permission to invade the South under the condition that Mao Zedong, the leader of China, would agree to send reinforcements if they became needed. Stalin made it clear that Soviet forces would not openly engage in combat to avoid a direct war with the Americans. Mao was concerned that the Americans would intervene but agreed to support the North Korean invasion. Once Mao’s commitment was secured, preparations for war accelerated. Soviet generals with extensive combat experience from World War II were sent to North Korea as the Soviet Advisory Group and completed the plans for the attack.

While these preparations were underway in the North, there were frequent clashes along the 38th parallel, many initiated by the South. The Republic of Korea Army (ROK Army) was being trained by the U.S. Korean Military Advisory Group (KMAG). On the eve of the war, KMAG’s commander General William Lynn Roberts voiced utmost confidence in the ROK Army and boasted that any North Korean invasion would merely provide “target practice.” For his part, Syngman Rhee repeatedly expressed his desire to conquer the North. Despite the southward movement of the Korean’s People’s Army (KPA), U.S. intelligence agencies and UN observers claimed that an invasion was unlikely.

Outbreak of the War

At dawn on Sunday, June 25, 1950, the Korean People’s Army crossed the 38th parallel behind artillery fire. The KPA justified its assault with the claim that ROK troops had attacked first, and that they were aiming to arrest and execute the “bandit traitor Syngman Rhee.” Fighting began on the strategic Ongjin peninsula in the west. There were initial South Korean claims that they had captured the city of Haeju and this sequence of events has led some scholars to argue that the South Koreans actually fired first. Within an hour, North Korean forces attacked all along the 38th parallel. The North Koreans had a combined arms force including tanks supported by heavy artillery. The South Koreans did not have any tanks, anti-tank weapons, or heavy artillery that could stop such an attack. In addition, South Koreans committed their forces in a piecemeal fashion and these were routed within a few days.

 

On June 27, Rhee evacuated from Seoul with some members of the government. On June 28 at 2 a.m., the South Korean Army blew up the highway Hangang Bridge across the Han River in an attempt to stop the North Korean army. The bridge was detonated while 4,000 refugees were crossing it and hundreds were killed. Destroying the bridge also trapped many South Korean military units north of the Han River. In spite of such desperate measures, Seoul fell that same day. A number of South Korean National Assemblymen remained in Seoul when it fell and 48 subsequently pledged allegiance to the North. On June 28, Rhee ordered the massacre of suspected political opponents in his own country.

 

In five days, the South Korean forces, which had 95,000 men on June 25, were down to less than 22,000 men. In early July when U.S. forces arrived, what was left of the South Korean forces was placed under U.S. operational command of the United Nations Command.

U.S. and UN Interventions

The Truman administration was unprepared for the invasion. Korea was not included in the strategic Asian Defense Perimeter outlined by Secretary of State Dean Acheson. Military strategists were more concerned with the security of Europe against the Soviet Union than East Asia. At the same time, the Administration was worried that a war in Korea could quickly widen into another world war should the Chinese or Soviets decide to get involved as well.

One facet of the changing attitude toward Korea and whether to get involved was Japan. Especially after the fall of China to the Communists, U.S. East Asian experts saw Japan as the critical counterweight to the Soviet Union and China in the region. While there was no United States policy that dealt with South Korea as a national interest, its proximity to Japan increased the importance of South Korea. However, a major consideration was the possible Soviet reaction in the event that the U.S. intervened. The Truman administration was fretful that a war in Korea was a diversionary assault that would escalate to a general war in Europe once the United States committed in Korea. Truman believed if aggression went unchecked, a chain reaction would be initiated that would marginalize the United Nations and encourage Communist aggression elsewhere.

On June 25, 1950, the United Nations Security Council unanimously condemned the North Korean invasion of the Republic of Korea with UN Security Council Resolution 82. The Soviet Union, a veto-wielding power, had boycotted the Council meetings since January 1950, protesting that the Republic of China (Taiwan), not the People’s Republic of China, held a permanent seat in the UN Security Council. After debating the matter, the Security Council on June 27, 1950, published Resolution 83 recommending member states provide military assistance to the Republic of Korea. On the same day, President Truman ordered U.S. air and sea forces to help the South Korean regime. On July 4, the Soviet Deputy Foreign Minister accused the United States of starting armed intervention on behalf of South Korea.

War of Attrition

After the first two months of the conflict, South Korean forces were on the point of defeat, forced back to the Pusan Perimeter. In September 1950, an amphibious UN counter-offensive was launched at Inchon and cut off many of the North Korean troops. Those that escaped envelopment and capture were rapidly forced back north all the way to the border with China at the Yalu River or into the mountainous interior. At this point, in October 1950, Chinese forces crossed the Yalu and entered the war. Chinese intervention triggered a retreat of UN forces which continued until mid-1951.

After these reversals of fortune, which saw Seoul change hands four times, the last two years of conflict became a war of attrition (a strategy in which a belligerent attempts to win a war by wearing down the enemy to the point of collapse through continuous losses in personnel and material), with the front line close to the 38th parallel. The war in the air, however, was never a stalemate. North Korea was subject to a massive bombing campaign. Jet fighters confronted each other in air-to-air combat for the first time in history and Soviet pilots covertly flew in defense of their communist allies.

Attributions