Battle of the Twin Tunnels - Korean war

The Battle of the Twin Tunnels took place during the Korean War. In which the 1st Battalion 23rd Infantry Regiment 3rd Brigade Combat Team 2nd Infantry Division and elements of the 21st Infantry Regiment 24th Infantry Division inflicted heavy casualties for the People's Volunteer Army.

A series of battles, including Twin Tunnels, the Battle of Chipyong-ni, and the Battle of Wonju between January and February 1951 marked a turning point in many ways for the entire Korea War. Importantly, these battles (especially Chipyong-ni on February 13–14, 1951) shaped the tactics that would replay throughout both Korea and Vietnam whereby well equipped isolated firebases, in communication by air and radio with regional divisional forces, held out against numerically superior light infantry formations. Eventually such tactics turned around the UN's disastrous retreat from the north into a stalemate that lead to an Armistice two years later relatively close to the site of these important battles.

See also:
http://www.cgsc.edu/carl/docrepository/1korstfride_km.pdf