Chosin Reservoir, Battle of the (1950).After the liberation of Seoul in September 1950, Gen. Douglas MacArthur opened an offensive aimed at ending the Korean War. The independent U.S. X Corps, separated from the Eighth Army by a mountain range, was stretched out on Korea's east coast. At the midway point, the First Marine Division was echeloned from Hungnam to the northwest along a mountain road to the Chosin Reservoir, an important hydroelectric plant.

On 24 November, MacArthur began an “end‐the‐war” attack to the Yalu. Days later, a massive Chinese counteroffensive erupted. The First Marine Division, its 5th and 7th Regiments now at Yudam‐ni north of the reservoir, was ordered to shift its attack to the west to shore up the collapsed right flank of the Eighth Army. Overwhelming Chinese forces quickly brought the Marine advance to a halt. Temperatures had dropped to −25° Fahrenheit.

The 1st Marines, the division's third infantry regiment, held positions in battalion strength at Hagaru‐ri, Koto‐ri, and Chinhung‐ni along the only road leading south from Yudam‐ni. Maj. Gen. Oliver P. Smith, the division commander, pulled the 5th and 7th Marines back to Hagaru‐ri. The breakout from there began on 6 December. Immeasurably helped by close air support and aerial resupply, the division reached Hungnam six days later. Of the some 15,000 Marines engaged, 4,400 were battle casualties. Almost all the Marines suffered some degree of frostbite. The Chinese had lost perhaps 25,000 dead and did not oppose the evacuation of Hungnam by X Corps, which was accomplished by Christmas.

Bibliography

Lynn Montross and and Nicholas A. Canzona , The Chosin Reservoir Campaign, 1957.
Roy E. Appleman , Escaping the Trap, 1990.

Edwin Howard Simmons