While awaiting the massing of United States power during the bleakest phase of World War II, England begins preparing for commando raids against Nazi-occupied Europe. As part of the desperate operation, the Allies create the 1st Special Service Force to plan and carry out an attack on Norway in hopes of tying up large numbers of German troops. The force of efficiently trained Canadian soldiers and rebellious American G.I. misfits is trained in Montana under the leadership of Lt. Col. Robert T. Frederick, a desk-bound army intellectual who has never before held a field command. Antagonism between the Canadians and the Americans, as well as between their respective leaders, Maj. Alan Crown and Maj. Cliff Bricker, at first threatens to disrupt the guerrilla training. But Frederick uses the men's mutual enmity as the basis for a rivalry that eventually welds them together as one highly disciplined fighting force. Shortly before they are scheduled for embarkation to Europe, the Canadians and Americans engage in a tavern brawl with some local lumberjacks, and, as a result of the free-for-all, the two groups of soldiers discover a camaraderie that had not heretofore existed on the surface. Then, when Frederick feels his outfit is ready for combat, he receives word that the Norway operation has been cancelled and the unit is to be disbanded. Appealing to Washington, he is granted a different assignment for his men--patrolling near the German lines in southern Italy. After capturing an enemy-held village, the unit is given the seemingly impossible task of taking Mt. La Difensa. Although the men accomplish their mission by scaling the precipitous mountainside, their losses are far greater than anticipated. Nonetheless, it is a telling victory--and one which earns for the 1st Special Service Force the grudging admiration of the Germans and the title "The Devil's Brigade."