Conferences and the Post-War International Order

From wartime allies to rival superpowers

During the Second World War, Britain, the USA and the USSR worked together in the Grand Alliance to defeat Nazi Germany. Their cooperation did not mean that they shared the same beliefs. Fighting a common enemy gave them a powerful reason to set their differences aside.

By 1945, the USA and USSR were emerging as the dominant superpowers. The central question was no longer simply how to defeat Hitler, but who would shape the post-war international order: the arrangements governing borders, governments, security and relations between countries. Once Germany surrendered on 8 May 1945, the common enemy that had held the alliance together disappeared. Disagreements about Europe's future became harder to contain.

The resulting Cold War was a struggle for power and influence rather than a direct full-scale war between the USA and USSR. Its early development involved a combination of incompatible beliefs, competing security interests and growing mistrust.

Why their visions of Europe differed

The USA was a capitalist democracy. Businesses were mainly privately owned, and its political system allowed competition between parties. American leaders emphasised individual freedom and wanted other countries to follow a similar political and economic model. They also wanted European economies to recover so that trade could resume.

The USSR was a communist one-party dictatorship under Joseph Stalin. The state directed the economy, and the Communist Party tightly controlled political life. Soviet ideology placed collective interests above individual rights; in practice, people had little freedom to challenge the government. Soviet leaders wanted communist influence to spread.

Security deepened these differences. Stalin wanted friendly governments along the USSR's western borders, creating a buffer zone against another invasion. Western leaders feared that this would mean Soviet domination rather than independent countries choosing their own governments. What Stalin presented as protection could therefore look like expansion to the West. Each side increasingly regarded the other's aims as a threat.

Yalta: planning peace while the war continued

The Yalta Conference took place on 4–11 February 1945, in the Crimea. The Big Three were Franklin D. Roosevelt, President of the USA; Winston Churchill, British Prime Minister; and Stalin. Germany's defeat appeared close, but the war was not yet over. The leaders still needed one another, and Roosevelt hoped that wartime cooperation could continue into peace.

They reached several important agreements:

• Germany: it would be occupied after defeat, with France included among the occupying powers. Germany would also pay reparations, although their precise arrangements remained unsettled.
• Eastern Europe: the Western leaders accepted that governments bordering the USSR should be friendly towards it. Stalin pledged to allow free elections in territories liberated from Nazi rule.
• Poland: its post-war government would include communists. The issue mattered because Poland lay between Germany and the USSR and was central to Stalin's security concerns.
• The United Nations: the leaders agreed arrangements for the Security Council, including five permanent members, each with a veto. This offered a framework for continued international cooperation.

Yalta appeared to show that agreement was possible. However, its promises contained a major tension: a government freely elected by its people might not be the government Stalin considered sufficiently friendly. Agreeing to elections did not settle who would actually hold power in Eastern Europe.

Why the atmosphere changed before Potsdam

Between the conferences, both the leadership and the military situation changed. Roosevelt died on 12 April 1945, and Harry Truman became US President. Truman's relationship with Stalin was poorer, and his administration challenged Soviet influence in Eastern Europe.

Germany's surrender then removed the immediate need for cooperation against Hitler. Meanwhile, the Red Army's presence in Eastern Europe gave Stalin considerable influence over the region's future. Western concern about Soviet conduct and control made the promises made at Yalta increasingly contentious.

There was also a new source of power. The USA successfully tested its first atomic bomb on 16 July 1945. Truman informed Stalin of the new weapon on 24 July, during the Potsdam Conference. American nuclear capability strengthened the US negotiating position, but it also increased tension. Stalin already knew about the programme through Soviet intelligence, so the announcement did not make him abandon his demands.

Potsdam: agreements amid growing mistrust

The Potsdam Conference ran from 17 July to 2 August 1945, near Berlin. Stalin represented the USSR and Truman represented the USA. Churchill initially represented Britain, but Clement Attlee replaced him on 26 July, after Labour's election victory.

Despite their worsening relations, the leaders confirmed important agreements about Germany. It would remain under four occupation zones, administered by the USA, Britain, France and the USSR. Germany was to be disarmed and demilitarised, Nazi influence removed, and war criminals brought to trial. A restored national German government was postponed, leaving the occupying powers responsible for administering the country.

These were occupation arrangements, not yet the creation of two separate German states. Berlin was also divided into four sectors, although the city lay within the Soviet occupation zone.

The most serious disputes concerned how these arrangements would work:

Reparations and recovery: Stalin wanted heavy compensation for Soviet wartime losses and a Germany too weak to threaten the USSR again. Truman and the British opposed demands that would cripple Germany's economy. They feared repeating the damaging consequences associated with the Treaty of Versailles. The settlement centred reparations on the occupying powers' own zones rather than resolving their conflicting priorities.

Poland and Eastern Europe: Western leaders feared that Stalin was gaining control rather than allowing genuinely independent governments. Poland's borders also shifted: it lost territory to the USSR and received territory previously belonging to Germany. The accompanying movement of German populations created further concern. These issues showed that deciding borders did not resolve disagreements about political freedom or security.

What the conferences changed

Yalta and Potsdam helped establish the machinery of the post-war settlement: Allied occupation of Germany, arrangements for Poland and cooperation through the United Nations. They therefore produced real agreements, not simply arguments.

Their wider significance was that they exposed the difficulty of maintaining the Grand Alliance. At Yalta, cooperation seemed possible, but important promises were open to conflicting interpretations. By Potsdam, leadership changes, Germany's defeat, Soviet influence in Eastern Europe and the atomic bomb had made mistrust more pronounced.

The conferences did not alone cause the Cold War. They revealed how underlying ideological differences became practical disputes over governments, territory and Germany's recovery. Those unresolved disputes helped turn wartime partners into post-war rivals.

Why the alliance weakened

• Defeat of Germany removed the common enemy.
• USA: capitalist democracy; wanted recovery, trade and governments following its model.
• USSR: communist dictatorship; wanted security through friendly neighbouring governments.
• Soviet buffer zone → Western fears of expansion and loss of political freedom.

Yalta, 4–11 February 1945

Roosevelt, Churchill, Stalin; Germany not yet defeated.

Agreements: Allied occupation of Germany including France; reparations; friendly governments bordering the USSR and promised free elections; communists included in Poland's government; UN Security Council veto arrangements.