In January 1943, at the Casablanca Conference, the Allies agreed to demand Axis unconditional surrender, a war aim which implied the physical occupation of Germany with land forces. While building up strength for an invasion of continental Europe, the Allies pursued an indirect strategy by invading Europe from the South. After defeating Axis forces in North Africa (the invasion of French North-Africa), Sicily and southern Italy were invaded, leading to the defeat of Fascist Italy. Churchill especially favoured a Southern strategy, aiming to attack the "soft underbelly" of Axis Europe through Italy, Greece and the Balkans in a strategy similar to the First World War idea of "knocking out the supports". Roosevelt favoured a more direct approach through northern Europe, and with the Invasion of Normandy in June 1944, the weight of Allied effort shifted to the direct conquest of Germany.