During the early days of World War II, while the United States was massing its forces for the war, England hastily plans commando raids against the German forces to keep them at bay until America's troops enter the war. As a part of this plan, the Allies create the 1st Special Service Force to plan and carry out an attack on Norway in order to tie up the German forces. This commando force of Canadian soldiers and American GIs is headed by Lt. Col. Robert T. Frederick (William Holden), a paper-pusher given his first field command. Antagonism immediately erupts between Canadian Maj. Alan Crown (Cliff Robertson) and American Maj. Cliff Bricker (Vince Edwards). But Frederick utilizes their mutual dislike as a basis for a rivalry that turns this rag-tag group of misfits into a disciplined fighting force. But now that Frederick's men are ready to fight, Frederick receives word that the Norway mission has been canceled. After appealing to Washington for another assignment for the commandos, the brigade is sent on a patrol near the German lines in southern Italy. The brigade captures an enemy-held village and is then given the seemingly impossible task of taking Mt. La Difensa.