The Potsdam Conference was the 1945 meeting where the Allied leaders decided how to handle postwar Europe, especially Germany, after World War II. The main participants were the United States, the United Kingdom, and the Soviet Union, represented by Harry S. Truman, Winston Churchill or later Clement Attlee, and Joseph Stalin.

What they agreed on

At Potsdam, the Allies agreed to divide Germany and Berlin into occupation zones, demilitarize and denazify Germany, and prosecute Nazi war criminals. They also set the Oder-Neisse line as Germany’s eastern border in practice, confirmed major changes affecting Poland, and discussed reparations and the removal of German industry that could support war.

Why it mattered

The conference showed growing tension between the Soviet Union and the Western Allies, especially over Poland, reparations, and the future of Eastern Europe. Historians often see Potsdam as one of the turning points that helped set the stage for the Cold War.

Japan and the war’s end

Toward the end of the conference, the Allies issued the Potsdam Declaration, demanding Japan’s unconditional surrender and warning of “prompt and utter destruction” if it refused. Truman also hinted to Stalin about a powerful new weapon during the conference.

A simple way to think about it is: Potsdam decided the rules for the defeated Germany, warned Japan to surrender, and exposed the growing split between the wartime allies.