The Outbreak of the Korean War in June 1950, the Chinese Volunteer Army entered the Korean War in October 1950, thus beginning the three-year Korean War, which profoundly affected the Korean Peninsula and the world pattern, in fact, from the end of World War II.

Three-eight lines
Japan's surrender on the Korean Peninsula
After all, the war of aggression will not be victorious and long-lasting, and Japan, which launched aggression in the Asia-Pacific and Pacific theaters, has finally reached the end of its rope. At noon on August 15, 1945, Emperor Hirohito of Japan broadcast to the whole of Japan accepting the Potsdam Proclamation and imposing an unconditional surrender to end the war.
Half a month later, on September 2, 1945, according to the Allied Agreement, MacArthur, the Supreme Commander of the Allied Forces, in his first instruction, used the 38th parallel north latitude as the boundary as the temporary demarcation line between the U.S. and Soviet armies to accept the surrender of the Japanese troops stationed in Korea and the temporary demarcation line for military activities against Japan, with the north as the surrender area of the Soviet troops stationed in korea and the south as the area where the American troops were surrendered. After Japan's surrender, U.S. and Soviet troops were stationed in the northern and southern regions of the 38th Parallel, which opened up the competition between the United States and the Soviet Union on the Korean Peninsula.
Japan surrendered unconditionally
Although Korea escaped Japanese colonial rule, it did not escape its bumpy fate.
In August and September 1948, the Republic of Korea and the Democratic People's Republic of Korea were established in the north and south of the Korean Peninsula. The Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea) decided from the very beginning of their founding that they would eventually go to war, because one was supported by the capitalist camp led by the United States and the other by the communist camp led by the Soviet Union!
Finally, on June 25, 1950, the Korean War broke out, and less than two days after the outbreak, the Washington government decided to enter the war, what caused the United States to decide to participate in this war as quickly as possible?
The Cold War energy has been accumulated for three years
Since the end of World War II in 1945, the Soviet Union and the United States, the two great powers that joined forces to end fascism, have "turned against each other" in less than a year, because both have the dream of a world power, but they have diametrically opposed political forms, and a protracted Cold War has begun. A multidisciplinary confrontation between the capitalist camp headed by the United States and NATO and the socialist camp headed by the Soviet Union and the Warsaw Pact organization, in addition to formal wars.
In 1946, Churchill's Iron Curtain address to the United States opened the prelude to the Cold War;
In 1947, the formation of the Truman Doctrine marked the beginning of the Cold War;
Former British Prime Minister Winston Churchill's Iron Curtain speech
U.S. President Harry S. Truman
Although there is still some time to go before the final bipolar pattern was formed in 1955, the Cold War had been accumulated for three years when the Korean War broke out, and the Korean pattern left by Japan's surrender in World War II undoubtedly provided the soil for the Cold War in the East.
The clamor of American politicians
Not long after the outbreak of the Korean War, the collapse of South Korea and its army completely stunned the politicians in Washington on the other side of the ocean, who felt that if South Korea and its army disintegrated, the Korean Peninsula would become a country under the full communist leadership, which would have a fatal impact on the US strategy of occupying Japan.
John. Foster. Dulles
One named John. Foster. Dulles's politicians (who, though arguably unknown in The Truman era, became secretary of state in the Essenhower administration) were notorious for their "war brinkmanship." It proposed to intervene in the situation on the Korean Peninsula even at the risk of Soviet action, which became the original U.S. course of action on the Korean Peninsula.
It can be said that this kind of thinking has basically become an epidemic, and all subsequent decisions have been made to prove that the invasion of North Korea is "nominally correct." Of course, as Dulles, there is no ability to influence anything, but U.S. President Harry S. Truman can.
Meeting of the Blair Building
Upon learning of the precariousness of South Korea and the imminent loss of Seoul, Secretary of State Acheson, who was in Tokyo, Japan at the time, in addition to referring the matter to the United Nations, also urgently called Truman, who spent the weekend in the Great Independence City of Missouri, and Truman flew back to Washington on the afternoon of the third day of the outbreak of the Korean War (June 26, North Korean time, June 25, U.S. time), and on the way back to Washington, Truman firmly decided to send troops to intervene in North Korea, and later said:
"If the free world allows the Communists to forcibly enter the Republic of Korea without interference, there will be no small states that resist aggression and threats in the face of powerful Communist neighbors."
On the evening of Truman's return to Washington, the first meeting was organized at the Blair Building. The first meeting was attended by Acheson and his aides, as well as representatives of the US Department of Defense and the military, and had serious consequences, although the decision at this time was not changed, but it basically strengthened the determination of all walks of life to send troops to North Korea, and basically achieved "the right will of the people".
It is said that a scholar of American politics, Alexeis. morality. As Tocqueville put it:
People elected as public leaders in the United States may often be untrustworthy or make mistakes, but they dare not deliberately make enemies of most people.
Because the main war faction led by the Republican Party and the "public opinion" that has been formed at home have made everything on the string.
Although the Security Council issued a resolution on the Korean Peninsula, it was apparently ignored by North Korea, and the North Korean offensive put Seoul in jeopardy, and Acheson could not sit still and asked Truman to meet again and make decisions as soon as possible. The second meeting of the Blair Building, held on 26 June, resulted in three decisive resolutions:
1. Lift restrictions on the U.S. Air Force and Navy, who can attack the North Korean army at any time, including armored troops and artillery;
2. At the current stage, the scope of the attack is limited to the south of the 38th Line, and it is not allowed to cross the 38th Line;
3. Order the Seventh Fleet to prevent military action between Taiwan and the Chinese Communist Party. (The third resolution is related to Acheson's visit to Japan and MacArthur, commander of allied forces in Japan, which is another story and will not be repeated here.)
In this way, under the guidance of these three guidelines, with the unexpected success of macArthur Inchon landings, the North Korean army was attacked on its back, and soon the situation on the Korean Peninsula underwent a fundamental change.
Cross the 38th Parallel and cross the Yalu River
However, even so, if the US military adheres to article 2 of the resolution and does not cross the 38th Line, then the situation on the Korean Peninsula is a different situation, but this is not the case. However, the U.S. State Department, however, acted within this framework in a vain attempt to destroy North Korea and establish a unified Korea ruled by Syngman Rhee on the Korean Peninsula, and did not hesitate to draw artillery fire to the Yalu River, and even to the border of Dandong and other places in China (although it was said to be a mistaken injury, but everyone knew it), which made China feel an unprecedented territorial threat.
The border between China and North Korea is separated by a river
On September 30, shortly after the successful landing at Inchon, Premier Zhou Enlai delivered a tough speech at the National Day Conference of the Chinese People's Political Consultative Conference:
"The Chinese people must not tolerate foreign aggression, nor can they allow imperialism to ignore the wanton aggression of its neighbours."
Before the massive entry of U.S. troops into the northern part of the Korean Peninsula in the early morning hours of October 3, Zhou Enlai summoned The Indian Ambassador to China, Paniga, and asked him to convey to the U.S. government:
"If the US military crosses the 38th Line and invades Korea, we will not sit idly by."
This warning was dismissed by Truman as China's "diplomatic blackmail" against the United Nations and was not taken seriously, but as China's declaration of war on the United States.
Troops to North Korea
In fact, from the outbreak of the Korean War to the time when the Chinese Volunteer Army fired its first shot in Korea, there were four months in between, and in fact, China was very entangled in whether to send troops to Korea. Because China has experienced many years of war and chaos, it is in ruins to be revived, and getting involved in this war is not conducive to national development.
Declassified soviet archives show that Stalin, as head of the socialist camp, instructed the CCP to intervene, but until early October, the Chinese government was still unable to make a final decision on whether to enter the war, and there was a lot of discussion in the middle:
In early October, Zhou Enlai rushed to Moscow to discuss the issue of joining the war with the Soviet side;
On October 4, 1950, Peng Dehuai, chairman of the Northwest China Military and Political Commission, was ordered to come to Beijing to discuss the Korean issue.
It was only at an enlarged meeting of the Politburo of the Central Committee of the Communist Party of China on October 8, 1950, that it was finally decided to intervene in the Korean War.
The direct reason for this decision was the bombing of China's Anton (present-day Dandong, Liaoning) by US aircraft, which seriously threatened China's territorial security, and macArthur, a war maniac, who could do anything, and if the United States occupied the Korean Peninsula, the consequences would be unimaginable.
Volunteers cross the Yalu River
Finally, the Chinese Volunteer Army went to Korea and launched a magnificent battle to "support Korea and defend the country"! Although victory was achieved after an arduous struggle, it was the price paid for being involved in the confrontation between the bipolar patterns.