Yalta, Potsdam and the changing order 1945-1948
From Alliance to Antagonism
In 1941, Britain, the United States, and the Soviet Union found themselves allied against Nazi Germany. By 1947–48, those same partners had hardened into opposing camps, dividing Europe along ideological lines that would define international relations for the next four decades. Understanding how that transformation happened requires examining two key wartime conferences, the decisions made in their aftermath, and the competing perspectives historians have offered about responsibility for the breakdown.
The two key conferences were Yalta (4–11 February 1945) and Potsdam (17 July – 2 August 1945). At Yalta, the Big Three agreed in principle on post-war Germany’s occupation zones, free elections in liberated Eastern Europe, and Soviet entry into the war against Japan. At Potsdam, a much cooler atmosphere prevailed: Truman had replaced Roosevelt, the USA had tested its first atomic bomb, and Stalin’s creation of a Soviet-dominated buffer in Eastern Europe was already apparent.
The Yalta Conference February 1945
The Yalta Conference brought together the three Allied leaders while Germany’s defeat was still weeks away. Yalta produced agreements on paper that were later contested in practice. Germany would be divided into four occupation zones, shared between the USA, Britain, France, and the Soviet Union. Berlin, deep inside the Soviet zone, would be similarly divided. Stalin committed to allow “free and unfettered elections” in Poland and other liberated states, a pledge that carried very different meanings in Washington and Moscow.
Roosevelt was already seriously ill at Yalta and died on 12 April 1945, before the war ended. His approach had been to seek Soviet co-operation through engagement — he believed that if the USSR was treated as a legitimate great power, it would act responsibly in the post-war order. Critics later argued he was too accommodating; supporters pointed out that the Red Army was already in Eastern Europe and the USA needed Soviet participation in the Pacific war.
The Potsdam Conference July–August 1945
By the time the three powers met at Potsdam, the context had changed dramatically. Germany had surrendered on 8 May 1945 (VE Day). Roosevelt had been replaced by Harry S. Truman, who was less inclined to accommodate Stalin. At Potsdam, Truman informed Stalin that the USA had “a new weapon of unusual destructive force” — the atomic bomb, tested successfully at Alamogordo on 16 July 1945. Stalin already knew about the Manhattan Project through espionage but gave no obvious reaction.
The Potsdam agreements confirmed the division of Germany and established the principle of reparations in kind from each zone. The Western powers grew increasingly concerned about Soviet actions in their occupation zone. Disputes about the German-Polish border, the treatment of German civilians expelled from Eastern Europe, and the nature of the governments being installed in Poland and Romania generated tensions that were not resolved before the conference ended.
Between 1945 and 1948, the Soviet Union systematically consolidated communist control across Eastern Europe. In Poland, Hungary, Romania, and Bulgaria, coalition governments that included non-communist parties were progressively dismantled — a process that Hungarian communist leader Mátyás Rákosi described as “salami tactics” — slicing away the opposition one piece at a time. The most dramatic example was Czechoslovakia, where a communist coup in February 1948 removed the last non-communist government in Eastern Europe.
On 5 March 1946, Winston Churchill delivered his famous speech at Fulton, Missouri, warning that “an iron curtain has descended across the Continent.” Churchill was no longer Prime Minister — he had lost the British general election in July 1945, replaced by Clement Attlee at Potsdam — but his speech captured the growing anxiety in the West about Soviet intentions. The Iron Curtain metaphor became the defining image of the emerging Cold War division.
Two Perspectives on Responsibility
Historians have long debated which side bears more responsibility for the breakdown of wartime co-operation. The orthodox, or traditional, view — dominant in Western scholarship from the late 1940s to the early 1960s — placed primary responsibility on Soviet expansionism. On this reading, Stalin pursued a calculated policy of extending Soviet power westward, breaking the Yalta pledges on free elections and using salami tactics to install puppet governments. The Western powers were reacting defensively to Soviet aggression.
The revisionist view, which emerged strongly from American scholarship in the 1960s, shifted the emphasis. Historians associated with this school argued that US atomic diplomacy — the possession and use of the atomic bomb — was a deliberate attempt to intimidate the Soviet Union. American economic expansion through aid programmes and trade agreements was characterised as “dollar imperialism.” The USA, on this reading, was not simply reacting but actively projecting power. It is worth noting that the Soviet Union had lost approximately 27 million people in the Second World War; Soviet leaders had security concerns that were genuine, not simply pretextual, whatever one concludes about the methods used to address them. Treat both views as live historical positions, not as a textbook version and a heresy.
The orthodox view holds that Soviet expansionism and the breaking of Yalta pledges drove the Cold War. The revisionist view holds that American atomic diplomacy and economic power projection were equally or more responsible. Post-revisionist historians (such as John Lewis Gaddis in later work) sought a middle ground, recognising both sides acted from genuine security fears in a system that generated misperception and mistrust.
The February 1948 communist coup in Czechoslovakia was a turning point in Western opinion. Czechoslovakia had maintained a coalition government and relatively free press longer than other Eastern European countries; its forcible takeover shocked Western publics and governments. Within weeks, the Western powers began serious discussions about a mutual defence pact that would become NATO in April 1949. The Czech coup also gave impetus to the Berlin Blockade crisis later in 1948, as Soviet pressure on Western access to Berlin further hardened the division of Europe into two camps.