North Korean invasion of the South Korean territories. The deadly conflict took thousands of lives on both sides, including many civilians. Initially the North was able to push the South Koreans back by many kilometers, however with assistance from the United States and the United Nations, the North was quickly overwhelmed by the superior firepower of the Western forces and quickly collapsed near the Chinese border. Fearing the Americans would not stop at North Korea, the Chinese decided to intervene and advance their forces into Korea. Caught by surprise, the Western forces were pushed back to the 38th parallel, where they remained in a stalemate until a ceasefire was negotiated. Technically the war has not ended, and both countries remain ready to fight each other again if it's necessary