1950
Battle of Chosin Reservoir
The setting
Chosin (Changjin) Reservoir, northeastern North Korea
Mountainous high-altitude plateau, single narrow mountain road (Main Supply Route), sub-zero winter conditions reaching -30 to -40 F
Reveal the outcome
Recorded sideUnited States / United Nations Command
Recorded resultsuccessful fighting withdrawal / breakout to Hungnam
Encircled UN forces, spearheaded by the 1st Marine Division, broke out southward through Chinese blocking positions and reached the port of Hungnam for evacuation; a tactical Chinese field victory but the UN force escaped intact while the Chinese 9th Army Group was rendered combat-ineffective largely by cold and casualties.
How the atlas explains it
Marine unit cohesion, disciplined perimeter defense, and consolidation before withdrawal ('retreating in a different direction'), combined with overwhelming close air support and control of the single mountain road, let an encircled force fight its way out. Chinese numerical superiority was blunted by inadequate winter clothing and logistics that inflicted enormous non-battle losses on the attackers.
What followed
One of the most celebrated fighting withdrawals in US military history; halted deep in North Korea it led to the evacuation of northeast Korea (Hungnam) and shaped the war's stalemate. Iconic example of small-unit discipline and combined air-ground operations in extreme cold.