On Friday, November 3, 1950 Mao Tse-Tung (1893 – 1976) ordered the Chinese Army to intervene in the Korean War on behalf of the the retreating North Korean Army:
"...perhaps [as many as] 250,000 Chinese Communists jumped into the battle for Northwest Korea; at best, their intervention meant a winter campaign in the mountains; at worst, a world war."
From Amazon: The Korean War: The Chinese Intervention
"The first surprise attack came at night. It was mounted by reckless fighters, who swarmed into battle on horseback and afoot after [American] bugles had morbidly sounded 'taps'. The Reds pounced on two combat regiments of the American First Cavalry Division and the South Korean First Division. Hundreds of civilians, caught by the flaming machine gun and mortar fire, were mowed down. In U.N. casualties, it was the one of the costliest engagements of the war."
Upon hearing the news of the Chinese Army's appearance on the Korean peninsula, President Truman turned to his trusted advisers:
"At 11 a.m. the President spoke first to General Bradley. How bad, he wanted to know, would the casualties be? 'Very bad, I'm afraid, sir. It is too early for an accurate estimate, but our losses will be heavy.' Then President asked how serious the situation was. 'Critical,' was Bradley's terse response."
"Man, those Chinese are good soldiers... You can't see 'em; you can't hear 'em. You don't know they're there until they're on top of you... They're experts at camouflage and the best damn night-fighters I've ever seen. We could walk a company over the hill and see nothing. Then we'd look around and they'd be swarming on us like flies. It was just like they'd sprouted from the ground."
With the expansion of the Korean War, the United Nations realized that World War III was at their doorstep if they wanted to engage. Withdrawing in order to fight another day made sense - but such a decision was not without costs.
The Chinese foray into Korea resulted in the coming together of numerous politicians in Washington in order to boost Army spending by $41.8 billion dollars, with an additional $1 billion designated for nuclear warfare preparedness. Assorted branches of the military increased the draft pool and lowered their admission standards. New Jersey Representative Charles Eaton (R) gravely stated:
"We face the greatest danger of extinction since the nation was founded."