The Americans and their United Nations allies faced terrible, mountainous terrain, which worked against their advantage in hardware, most notably their armored vehicles, and offered caves and other forms of shelter to the enemy. 'The century's nastiest little war,' the military historian S. It was a war fought on strikingly harsh terrain and often in ghastly weather, most particularly a numbing winter cold that often seemed to American troops an even greater enemy than the North Koreans or Chinese. The Korean War would last three years, not three weeks, and it would be the most bitter kind of war, in which relatively small American and United Nations forces worked to neutralize the superior numbers of their adversaries by the use of vastly superior hardware and technology. Was this, as they feared, an assault ordered up by the Russians? Were the North Koreans nothing but Moscow's pawns? Or was it a feint, the first in a series of what might be provocative Communist moves around the world? They quickly decided to use United States, and in time United Nations, forces to draw a line against Communist aggression in Korea.

In Washington President Harry Truman and his top advisers debated the enemy's intentions. Every bit of news from the battlefield was negative. In the early weeks of the invasion, the Communist offensive was a stunning success. Some six months earlier, Secretary of State Dean Acheson, in a colossal gaffe, had neglected to include South Korea in America's Asian defense perimeter, and the only American forces then in the country, part of a tiny advisory mission, were almost completely unprepared for the attack. On June 25, 1950, nearly seven divisions of elite North Korean troops, many of whom had fought for the Communist side in the Chinese civil war, crossed the border into South Korea, with the intention of conquering the entire South in three weeks.

The Coldest Winter by David Halberstam