Key point: China's intervention into the war took American and United Nations forces completely flat-footed.
The 1st Marine Division was on the move toward the Yalu River. With any luck, if the weather cooperated, the United Nations police action in Korea would be over in weeks.
The 5th Marine Regiment (5th Marines), most of the 7th Marines, and three artillery battalions of the 11th Marines spent the daylight hours of November 27, 1950, staging into the North Korean mountain-valley town of Yudam-ni, on the frozen shore of the Chosin Reservoir. While company-size units of the 7th Marines patrolled and fought through the day to secure the far-flung ridge lines that dominated the valley, a battalion of the 5th Marines mounted a limited assault aimed at striking off into the unsecured hinterland of North Korea.
Strangely, for the Marines had faced no serious opposition in more than a month, all their patrols, sweeps, and advances on November 27 were strongly contested. Unbeknownst to the Marines, tens of thousands of Chinese People’s Liberation Army (PLA) soldiers were set to spring an enormous trap on the main body of the 1st Marine Division.
Isolated and Unaware
The temperature was minus 30 degrees F, so by 9 pm all but the regular watchkeepers were snuggled in their soft down sleeping bags, shoeless and exhausted by the day’s prodigious physical exertions and the sub-zero cold.