The Korean War was a military conflict between North and South Korea that lasted from June 25, 1950 to July 27, 1953. The North invaded the South on June 25, 1950, in an effort to unify the country under communist rule. The United Nations, led by the United States, intervened on behalf of South Korea, and a coalition of UN forces, primarily from the United States, fought against the North Korean and Chinese armies. The war was marked by brutal fighting, with heavy casualties on both sides. A ceasefire was declared on July 27, 1953, and a demilitarized zone was established along the 38th parallel, which still serves as the border between North and South Korea today. The Korean War resulted in the deaths of millions of people and left the Korean Peninsula divided and heavily militarized.