Role of China in the Korean War
When US entered the Korean War, they kept pushing the North Koreans back even when they were already past the 38th parallel. Truman warned General MacArthur to stop but he kept going. As they got closer to China, they felt that if they didn't react fast then the UN forces would push into their borders and that was exactly what Truman was worried about. China even warned the US that they shouldn't go anywhere near their border but US forces just wouldn't stop. In late October of 1950, Truman flew over to confer with his General, MacArthur, about the threats but he assured him that China wouldn't intervene and they would win the war. He was wrong because in November, when the US troops closed in on the Chinese border the Chinese carried out their threat with 200,000 troops. They were usually massive infantry attacks because they did not have much of an air force or a sufficient amount of tanks. This left the UN troops totally outnumbered and they were pushed out of North Korea and lost the South Korean capital once again ( Seoul ) before the lines were stabilized with fresh troops. MacArthur wanted to get back at China with bomb raids, nuclear weapons, etc. but was fired.
Implications :
Without China, there would have probably been no chance for North Korea. Perhaps if MacArthur had left North Korea alone without pushing them back to the extent that they were reaching China's border then the war wouldn't have been extended. Because of China, the UN forces were pushed back and even lost South Korea's capital and many of their men. China was vital for North Korea's survival in the war.