The Battle of Triangle Hill (上甘岭战役) was a protracted military engagement during the Korean War that pitted two United Nations infantry divisions and the US Air Force, against elements of the 12 and 15th Corps of the Chinese People’s Volunteer Army (PVA).
The battle was part of UN attempts to gain control of “The Iron Triangle“, and took place from 14 October to 25 November 1952.
Despite superiority in artillery and aircraft, after 42 days of escalating UN casualties, the attack was called off and PVA forces regained their original positions.