The August First Film Studio Documentary, the Battle of Changjinho, the eastern front of the second campaign to resist U.S. aggression and Aid Korea, was the bloodiest battle of the Korean War. At that time, the 9th corps, with a strength of 160,000, successfully divided and encircled the U.S. Army’s 1st Marine Division and 7th Infantry Division in the north-eastern region of Changjinho, about 30,000 men. However, due to the cold, shortage of supplies, fire gap and the air superiority of the US army, the volunteers failed to achieve the objective of annihilating the 1st Marine Division, and paid a heavy cost of more than 60,000 casualties. The near-death death death of the 1st Marine Division also boosted the confidence of the US military and political leadership, ultimately establishing its determination to continue the Korean War.