During the early days of World War II, England hastily plans commando raids against the German forces to keep them at bay until the United States finishes massing its forces and starts sending America's troops into battle. In order to tie up the German forces and as a part of England's plan, the Allies create the 1st Special Service Force to prepare and carry out an attack on Norway. Antagonism immediately erupts between Canadian Maj. Alan Crown (Cliff Robertson) and American Maj Cliff Bricker (Vince Edwards) when this commando force, composed of Canadian soldiers and American GIs, is headed by Lt. Col. Robert T. Frederick (William Holden), a paper-pusher given his first field command. Frederick utilizes their mutual dislike as a basis for a rivalry that turns this rag-tag group of misfits into a disciplined fighting force. Frederick receives word that the Norway mission has been canceled after his men finally seem ready to fight. 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.