The Korean war

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TABLE OF CONTENTS

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The Korean War was the first major conflict of the Cold War, fought from 1950 to 1953. It was a proxy war between the United States and the Soviet Union (USSR), which each supported the regional conflict by sending troops and supplies directly to their allies. The United States backed South Korea whilst North Korea was backed by the Soviets and China. Which side won the Korean War, and what caused the conflict anyway?

Proxy war

An armed conflict fought between countries or non-state actors on behalf of other powers not directly involved.

Korean War dates

The Korean War was fought from 25 June 1950 – 27 July 1953, when an armistice was signed between North Korea, China, and the United States. However, South Korea did not agree to this armistice and no formal peace treaty has ever been signed, so technically the Korean War never ended.

Korean War Korean War illustration StudySmarter Fig. 1 - Korean War illustration

Background of the Korean War

Let’s look at what was going on in Korea before the Korean War in order to fully understand the causes of the war.

Imperial Japanese rule: 1910–45

Korea had been part of Japan since 1910 after it was annexed in the Japan–Korea Annexation Treaty. Imperial Japanese rule led to many Korean nationalists fleeing the country and installing the Provisional Government of the Republic of Korea in China in 1919. This government failed. It did not receive international support; it did not unite Koreans; and its founder, Syngman Rhee, was based in the United States for the majority of his time as President, making it more difficult for him to remain in touch with what was happening in Korea.

In China, Korean refugees were organised to fight against the Japanese military thanks to the Nationalist Chinese National Revolutionary Army and the Communist Chinese People's Liberation Army (PLA). Between 1919 and 1945, Korean nationalists fought the Japanese through direct and indirect warfare. Led by Yi Pom-Sok, they took part in the Burma Campaign (1941–45) and fought the Japanese in Korea and Manchuria.

At the Cairo Conference in November 1943, the United Kingdom and the United States met with the President of China to discuss securing the surrender of Japan and plans for post-war Asia. Regarding Korea, the three powers declared that:

in due course Korea shall become free and independent.

Dividing Korea

In February of 1945, at the Yalta Conference, the Soviet Union agreed to join the United States in the Pacific War to defeat Japan once Germany had surrendered. When the USSR entered into the war against Japan on 8 August 1945, it promised to support the independence of Korea. The Soviets first invaded Manchuria and by 10 August, the Red Army occupied the north of Korea.

By this time, US Colonels in Washington had been assigned to divide Korea into two different occupation zones: one for the Soviet Union and one for the United States. It was divided into a Northern and Southern zone; the dividing line is known as Parallel 38. Soviet leader Joseph Stalin respected his wartime alliance and cooperated: his troops halted at the 38th Parallel on 16 August and waited three weeks for US troops to arrive from the South.

Korean War Members participating in a Jewish worship service in the field during the Korean War StudySmarter Fig. 2 Members participating in a Jewish worship service in the field during the Korean War

The US government then decided to hold an election in order to create an independent and unified Korea in 1948 but the USSR and Korean communists refused.

A general election was held in the South on 10 May 1948. The South Korean government then published a national political constitution two months later, and Syngman Rhee was elected as President. The Republic of Korea was established on 15 August 1948. In the Soviet zone, a communist government led by Kim Il-sung was established.

In 1948, the USSR withdrew its troops from Korea, followed by the US in 1949.

Immediate causes of the Korean War

Korea was now divided between the non-communist, American-backed South Korea under the leadership of Syngman Rhee - an anti-communist statesman, and the Soviet-backed communist North Korea, ruled by Kim Il-Sung - a dictator. How did this situation transpire into war?

North Korean attacks

Many South Koreans believed that the Rhee regime was corrupt and had manipulated the election of 1948 in order to win it. This made Syngman Rhee an extremely unpopular leader and he fared badly in the April 1950 elections. Many in the South voted for reunification with the North.

This caused North Korea to launch an attack on South Korea on 25 June 1950, with the support of China and the Soviet Union. More than 80,000 North Korean troops invaded and captured the South Korean capital, Seoul, in just 3 days. The Korean War had only just begun…

Korean War combatants

As we have mentioned, the Korean War was not simply a war between North and South Korea. The involvement of other countries was influential on the beginning and course of the Korean War.

Combatant	Motives
United States	Domino Theory As North Korea invaded practically the whole of South Korea, including its capital, the United States was desperate to not only contain the spread of communism but also prevent the domino effect. Harry Truman, the US president at the time, was worried that if Korea fell to communism, other countries in Asia would fall, which would be catastrophic for America and for capitalism. Fig. 3 - Domino Theory cartoon The Truman Doctrine The Truman doctrine (named after President Harry Truman) was the name of an American foreign policy introduced in 1947 which declared that the US would help any country under the threat of communism and authoritarianism. In this case, South Korea was invaded by communist forces, so the US came to its aid. Other factors The US believed that Stalin was helping the North Koreans invade South Korea. The US believed it could guarantee a swift victory if China did not intervene. Truman hoped to get UN military support to speed up the operation. The US was determined to have a victory against the Soviet Union given the advance of communism in other parts of the world e.g. China's "fall" to communism, or the USSR testing its first atomic bomb in 1949.
The Soviet Union	Spread of communism The Soviet Union believed in spreading communism across the world. Since Kim-Il Sung was attempting to do this with South Korea, Stalin felt it was necessary to help him. At the same time, the UN was sending help to South Korea, so the USSR had to counter this by helping North Korea. Avoiding direct confrontation with the US Stalin wanted to expand communism covertly and not get involved in a direct confrontation with the United States (known as a “hot war”). The Korean War was a perfect way to do this by simply supporting local North Korean, as well as Chinese, troops. If North Korea successfully took over South Korea, this would increase the USSR’s influence in Asia.
China	Buffer zone China’s leader, Mao Zedong, was alarmed by the proximity of UN forces to his border and even feared an American invasion. Mao wanted North Korea to act as a buffer zone for China, and for this, had to help North Korea remain a communist country. Sino-Soviet Treaty The Sino-Soviet Treaty of Friendship, Alliance, and Mutual Assistance with the USSR meant that Mao was under pressure from Stalin to help North Korea.

Military action during the Korean War

From the end of the Second World War, until 25 June 1950, when war broke out, the dividing line between North Korea and South Korea had been the 38th parallel. The maps below show the division of Korea before and after the Korean War. So, what happened during three years of fighting for the end result to be so similar to the start?

The course of the Korean War

Let’s study briefly the course of the war.

Step 1: North push into the South

Between June and September 1950, the North Korean People’s Army (NKPA) invaded South Korea swiftly and pushed the Southern forces all the way to Pusan. During this time, the US sent troops to support South Korea, aided by the United Nations Security Council, which also agreed to send military support.

Korean War Flag of the Supreme Commander of the Korean People's Army StudySmarter Fig. 4 - Flag of the Supreme Commander of the Korean People's Army

Step 2: UN Offensive into the North

By September 1950, UN forces led by General MacArthur were ready to launch a counterattack on North Korea. They surprised the NKPA by launching an amphibious invasion at Inchon on 15 September 1950, quickly pushing the North Koreans back over the 38th parallel. By November, they had almost pressed the communists to the Chinese border, along the Yalu River.

Step 3: Entry of China

On 27 November 1950, China decided to invade Korea since it did not want a US-backed state right on its border and it became increasingly concerned about an attack on their country. Around 200,000 Chinese troops joined 150,000 North Korean troops and by the end of 1950, the UN forces were driven back below the 38th parallel.

Step 4: Stalemate

By early 1951, there were over 400,000 Chinese troops in Korea; it was difficult to keep this number of troops equipped with supplies. This factor combined with the extensive bombing of the North by UN forces to the detriment of the North. On the other hand, UN forces were threatened by widespread guerilla activity.

The war came to a stalemate. The Chinese led many offensives trying to break through, one of the most notable being the Chinese Spring Offensive. This operation mobilised more than 700,000 men from the PLA during the summer of 1951 and aimed at permanently driving the UN forces off the Korean peninsula. Although initially successful, the Chinese were halted by 20 May. The US Army then counterattacked the exhausted Chinese forces, inflicting heavy losses, but managed to hold firm near the 38th Parallel.

The stalemate continued, as did the heavy bombing and fighting.

The firing of General MacArthur

MacArthur wanted to use atomic bombs against China to reduce Chinese aid to North Korea. This caused tension between him and President Truman. MacArthur wanted to push further North and expand the conflict to liberate North Korea from communism in keeping with the idea of rollback - converting communist nations to capitalism. Truman on the other hand wanted to act on the policy of containment and prevent communism from spreading into South Korea.

Korean War President Truman StudySmarter Fig. 5 - President Truman

MacArthur's repeated pleas to use atomic bombs against China and expansion of the conflict led Truman to fire the general on 11 April 1951, who was replaced by General Matthew Ridgway.

Step 5: Peace talks

Peace talks began in July 1951 but soon broke down. In November 1952, newly elected but not yet integrated president, Dwight Eisenhower went to Korea in a bid to end the war. In July 1953, an armistice was finally signed between North Korea, China, and the USA.

Did you know?

For two years, the war was fought in the skies, between American and Soviet pilots! The Soviet pilots were dressed in Chinese uniforms and flew planes with Chinese markings. Technically, the US and USSR were engaging in direct conflict, which could lead to a declaration of war. For this reason, the aerial battles were kept secret from the US population, in case they demanded an all-out war with the USSR.

Comparative roles of China and the USSR

Chinese actions

Soviet actions

China sent over 2 million soldiers to Korea.
The Chinese frequently launched human wave assaults against the South - a dense unprotected assault intended to overwhelm the enemy. This tactic led to huge casualties but was practically the only option to the Chinese as they lacked heavy weapons and armoured vehicles to create a more sophisticated strategy.
Mao felt betrayed by the USSR which did not send infantry or tanks to assist the Chinese effort.

The USSR did not send ground troops to fight in the Korean War.
The USSR provided material and medical services, even sending MiG fighter jets over Korea.
Soviet pilots flew planes with Chinese markings and supposedly shot down over 400 UN aircraft.

Panmunjom Armistice

The Korean War formally ended on 27 July 1953, when an armistice was signed at Panmunjom on the 38th parallel. The Panmunjom Armistice was the conclusion of the longest negotiated armistice in history: it lasted over two years and took 158 meetings to achieve.

Armistice

A formal agreement made by groups or countries at war to stop fighting.

The Korean Armistice Agreement is unique since it is purely a military document. Since there has never been a peace treaty, North Korea and South Korea are still at war to this day as we mentioned earlier!

The armistice did, however, allow for all military forces and equipment to withdraw in order to create a 4km wide Demilitarized Zone. It also prevented both countries from entering the air, ground, or sea spaces under the control of the other.

Consequences of the Korean War

Let's look at the consequences of the Korean War for all parties involved in the table below.

Country/group	Consequences
Korea	Korea was devastated: many people had lost their lives and even more had been made homeless. Hope for the reunification of Korea was gone. Families living across the new dividing line were unable to visit or communicate with each other. South Korea was quickly rebuilt due to US investment, and Syngman Rhee's leadership was protected by the US. North Korea remained under communist rule, and without the investment given to South Korea, many North Koreans faced absolute poverty.
China	The war was costly in both lives and resources for China. China emerged as a third superpower, having taken on UN forces and been instrumental in the course of the war. China's involvement meant that it appeared as the leader of the communist movement in the region, compared to the USSR. China no longer trusted the USSR and began to distance itself, ultimately resulting in the 1960 Sino-Soviet Split.
USSR	The USSR had lost its standing in Asia compared to China, and tensions between the two powers intensified. The Cold War intensified after the Korean War, and Stalin increased military spending.
USA	The US succeeded in containing communism in Korea. After the Korean War, the US implemented recommendations from NSC-68 - a 1950 US Security Council report which guided US foreign policy. This led to further commitment to containment through measures such as tripling its defence budget. The domino theory remained a staple of US foreign policy decision-making for the rest of the Cold War. The US established a series of treaties in Asia to reinforce its influence in the region, including an alliance with the Philippines. It also signed the ANZUS Pact with Australia and New Zealand in 1951. Japan was rebuilt and the US ended its occupation of the country in 1951. This same year, the US signed a security treaty with Japan, which meant it could station troops there. Japan became vital to US containment now the Cold War had spread to Asia. The US decided it would no longer have any relations with China, and was increasingly committed to protecting Taiwan from Chinese communism.
UN	Respect for the UN in developing nations declined after the war, as it was seen to be a tool of the US.

Korean War casualties

The casualties of the Korean War were huge, and though estimates vary, over four million military and civilian lives were lost. Over half of the people that died in the Korean War were civilians.

Some statistics on military casualties include:

Around 137,000 South Koreans were killed.
Around 520,000 North Koreans were killed.
Around 40,000 UN soldiers were killed.
Around 116,000 Chinese soldiers were killed.¹

These numbers do not include those wounded or missing.

Consequences for the Cold War

The Korean War led to the globalisation of the Cold War, with the superpowers now involved in conflicts in Asia rather than just Europe. The US had proved it was willing to intervene when communism threatened non-communist states globally. As well as globalising, the war also intensified with the increase in military spending.

US military spending

Between 1950 and 1953, the defence budget more than tripled, reaching its peak in 1952 during the war.

1950: $13 billion
1951: $48 billion
1952: $60 billion
1953: $47 billion²

The Korean war - Key takeaways

The Korean War was a major conflict of the Cold War period, between North Korea and South Korea. It reached international proportions when the United Nations and US troops intervened to help the South. The fighting ended in July 1953 with the Panmunjom Armistice, and Korea is still divided to this day into two hostile states.
The Korean War started in June 1950 when North Korea commenced the invasion of South Korea. The US, following its policy of containment, intervened. This is along the lines of the so-called domino theory: the US feared that if one country fell to communism, then other countries would follow.
The USSR and China both supported North Korea by supplying soldiers, weapons and medical supplies. However, they eventually distanced themselves as China grew weary of the Soviet Union as an ally. This was called the Sino-Soviet Split.
The Korean War had repercussions around the world and in Korea. South Korea prospered thanks to capitalism, whilst a ruthless dictatorship was installed in North Korea and the majority live in poverty, even today. The US, following the end of the war, set up alliances in Asia to strengthen its grasp on the region.

References

1. L. Yoon, ‘Number of military casualties during the Korean War 1950-1953’, Statista (2021).

https://www.statista.com/statistics/1131592/korean-war-military-casualties/.

2. Samuel Wells, ‘Korea and the Fear of World War III’, Wilson Center (2020). https://www.wilsoncenter.org/blog-post/korea-and-fear-world-war-iii.

Frequently Asked Questions about The Korean war

The Korean War started on 25 June 1950, when North Korea invaded South Korea, and ended on the 27 July 1953 when the Panmunjom Armistice was signed.

No country officially won the Korean War. After three years of bloody conflict, the countries involved - the US, China, North Korea and South Korea - agreed to an armistice, which ended all hostilities.

However, if we take into account each country’s goals, then it is clear that the US won the war since it was successful in stopping communism from spreading to South Korea.

Over four million people died during the Korean War. Of these, more than half were civilian casualties.

The Korean War was the first major conflict of the Cold War, fought between North Korea and South Korea. It reached international proportions in June 1950 when the United Nations and US troops intervened to help the South. The fighting ended in July 1953 with the Panmunjom Armistice. Korea is still divided to this day into two hostile states.

Historians agree that several issues caused the Korean War. These included the spread of communism during the Cold War, America’s policy of containment, and the Japanese occupation of Korea.

In fact, because Japan occupied the Korean Peninsula between 1910 and 1945, the US and USSR had to liberate the region during WWII. The Soviet Union invaded the northern half of Korea whilst the United States liberated the southern half. As the two sides could not agree on uniting the country, it was split into two halves along the 38th parallel. This created tensions between North and South Korea as each side promoted very different ideologies, which ultimately led to North Korea invading South Korea. This in turn led to the outbreak of war. America intervened soon afterwards by sending troops to support the South in a bid to prevent the spread of communism.

Flashcards in The Korean war42 Start learning

What happened to Korea in 1910?

Japan annexed Korea in 1910 with the Japan-Korea Annexation Treaty.

What did Korean refugees do between 1919-1945?

Between 1919 and 1945, Korean refugees joined China’s military and fought against the Japanese during the Burma Campaign, in Korea and Manchuria.

What was decided at the Cairo Conference concerning Korea?

The United Kingdom and the United States met with the president of China and decided that "Korea [should] become free and independent".

What was the state of Korea in 1945?

Korea was divided into two separate states, the North occupied by the Soviets and the South controlled by the United States.

What was the state of Korea in 1945?

Korea was divided into two separate states, the North occupied by the Soviets and the South controlled by the United States.

What was the state of Korea in 1945?

Korea was divided into two separate states, the North occupied by the Soviets and the South controlled by the United States.

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