In the opening scene, German troops and tanks are shown invading the Kingdom of Yugoslavia while bombers attack the capital Belgrade. When Nazi Germany, Italy, Hungary, and Bulgaria invade Yugoslavia on 6 April 1941, Serbian army colonel Draža Mihailović forms a band of guerrillas known as the Chetniks, who launch a resistance movement against the Axis occupation. Mihailović's forces then engage in an attack on the German and Italian forces, forcing them to employ seven Axis divisions against them.