Who was involved and why?

Kim il Sung (1912-1994): The dictatorial leader of North Korea after World War 2, up until his death in 1994.

Douglas MacArthur (1880-1964): Powerful Military officer in the American history, he was the Allied Commander of Southwest Pacific Theater during World War 2.

Syngman Rhee (1875-1965): an American educated Korean exile, went back to his country to become not only the president but the first president.

Soviet Union and china: invaded South Korea and was supported by the United States.

United States:General MacArthur drove the North Korea back across the 38th parallel.