Two summits in 1945 established the territorial and political framework in which the Cold War would be fought. The Yalta Conference, February 4–11, brought together Roosevelt, Churchill, and Stalin in the Crimean resort town. The Potsdam Conference, July 17 – August 2, replaced Roosevelt with Truman and Churchill with Attlee and inherited most of the same agenda. By the time Potsdam ended, the wartime alliance was already fracturing.
Yalta: The Last Wartime Bargain
Yalta was the most important of the wartime summits. The Red Army had driven the Wehrmacht out of Soviet territory and was closing on Berlin from the east. The Western Allies had liberated France and were pushing into western Germany. The Pacific war was still expected to last at least another eighteen months — the atomic bomb had not yet been tested. Stalin held the military cards in Europe; the United States held them in the Pacific; Britain held the weakest hand of the three.
The substantive results were a set of compromises. The three leaders agreed on the structure of the new United Nations, including the controversial veto power of the five permanent Security Council members. They agreed that Germany would be divided into four occupation zones (American, British, French, and Soviet) and that Berlin, deep in the Soviet zone, would also be divided. The future of Poland, the most contentious issue, was settled by a face-saving formula in which the Soviet-backed Lublin government would be “reorganized on a broader democratic basis” and “free and unfettered elections” would be held “as soon as possible.” The word “unfettered” was the principal Western concession; Stalin’s interpretation of it was, in the event, decisive.
In a secret protocol unknown to the Chinese Nationalist government, Stalin agreed to enter the Pacific war two to three months after Germany’s surrender in exchange for the southern Kurils, southern Sakhalin, leasehold rights at Port Arthur and Dairen, and recognition of the Mongolian People’s Republic. Roosevelt calculated that Soviet entry would save American lives on Kyushu. The deal was made in the language of great-power realism that the war had made possible.
Potsdam: The Bargain Unravels
Potsdam opened on July 17, 1945, four days after the Trinity test in New Mexico. Truman received the news of the successful bomb at the conference table and mentioned it to Stalin in carefully oblique terms. Stalin, whose own intelligence had tracked the project, feigned indifference.
The principals had changed. Roosevelt was dead; Truman was in his 80th day as president and would be tested on the world stage for the first time. Churchill was replaced midway through the conference by Clement Attlee after the British general election. The atmosphere was markedly more tense than at Yalta. Stalin had no intention of permitting the free elections he had agreed to in February. Truman, in turn, was under orders from a public that had turned against the Soviet Union while Roosevelt was still alive.
The conference produced a series of communiqués, the most important of which established the basic machinery of the four-power occupation of Germany, a Council of Foreign Ministers to draft peace treaties, Oder-Neisse line as the provisional western border of Poland pending a final peace settlement. The question of German reparations — Stalin wanted $20 billion, with half going to the USSR; the Americans and British considered any fixed figure premature — was deferred to a special commission that never reached agreement. That failure would contribute directly to the Berlin Blockade of 1948–1949.
Potsdam also produced the Potsdam Declaration of July 26, 1945, an ultimatum to Japan calling for unconditional surrender. The Japanese government’s reply, the famous mokusatsu — “we will maku it” or “we will ignore it” — was read in Washington as a rejection. Twelve days later, Hiroshima was destroyed.
The Cold War That Followed
The two conferences are often treated as a single moment of great-power accommodation that “divided Europe.” That framing is incomplete. Yalta and Potsdam did not create the Soviet sphere in Eastern Europe; the Red Army created it by being there. The conferences ratified a military reality and put a thin diplomatic veneer over it. Within thirty months, the veneer had cracked open over Berlin, and the Cold War was underway in earnest.
Key dates, 1945
| Date | Event |
|---|---|
| 1945-02-04 | Yalta Conference opens in Crimea (Roosevelt, Churchill, Stalin). |
| 1945-04-12 | Franklin Roosevelt dies; Harry Truman becomes U.S. president. |
| 1945-05-07 | Germany signs unconditional surrender at Reims (V-E Day). |
| 1945-07-16 | Trinity test at Alamogordo, New Mexico — first nuclear detonation. |
| 1945-07-17 | Potsdam Conference opens outside Berlin. |
| 1945-07-26 | Allies issue the Potsdam Declaration demanding Japan’s unconditional surrender. |
| 1945-08-06 | ”Little Boy” dropped on Hiroshima, Japan. |
| 1945-08-09 | ”Fat Man” dropped on Nagasaki, Japan. |
Key sources
- Diane S. Clemens, Yalta (1970)
- Fraser J. Harbutt, The Iron Curtain: Churchill, America, and the Origins of the Cold War (1986)
- Sean McMeekin, Stalin’s War: A New History of World War II (2021)
- Geoffrey Roberts, Stalin’s Wars: From World War to Cold War, 1939–1953 (2006)