North Korea and South Korea divide themselves in half at the 38th parallel because NK believe in communism and SK believes in democracy.
North Korea crosses the 38th parallel in a surprise attack on South Korea
The United Nation troops intervene to help South Korea push back North Korea
UN troops and South Korean troops push back the north to the Yalu River
The north pushes the south back to the 38th parallel
The north and south sign a armistice to end the war