Final answer:
The Allied leaders held conferences starting in 1943 to decide on a strategy to defeat the Axis powers and to make plans for the postwar world, including the division and demilitarization of Germany and preventing another world war and economic depression.
Step-by-step explanation:
The Allied leaders began to hold conferences starting in 1943 to strategize the defeat of the Axis powers and to plan for the postwar world. The Tehran Conference in November 1943, which involved leaders such as Roosevelt, Churchill, and Stalin, focused on the demand for an invasion of France as well as post-war planning. The goal was not only to determine military strategies but also to consider the best ways to avoid another world war and economic distress similar to the Great Depression. The concept of the United Nations became an early framework for this collaboration.
At the Yalta Conference in February 1945, the "Big Three" set plans for Germany's unconditional surrender and its postwar division into four zones controlled by the Allies. They also dealt with future policies for European nations, with Stalin initially agreeing to free elections in Eastern Europe. The Allied powers also agreed to demilitarize and decentralize Germany to focus on agriculture and nonmilitary industries at subsequent conferences.
Finally, at the Potsdam Conference in July 1945, decisions were finalized about the occupation zones in Germany and Austria, as well as the dismantling of German heavy industries. During the war and these conferences, the main objective was to ensure a lasting peace and the reconstruction of war-torn countries while preventing any single nation or leader from pursuing policies that might lead to future conflicts.