Why the wartime alliance broke up

G2 Full History - syllabus K227, 2027

What this lesson teaches

  • I can explain how rivalry between the USA and the USSR after 1945 divided Europe and shaped the Cold War.

    Syllabus K227, The Cold War, Learning Outcomes. Explain the impact of rivalry between the USA and USSR in the aftermath of World War II.

Make a guess

The USA, Britain and the USSR won the war together in 1945. What do you think happened to their alliance once Germany was beaten?

  1. It grew stronger, because they had learnt to trust each other.
  2. It quickly turned into a shooting war between the USSR and the West.
  3. It broke down as disputes over Germany and Eastern Europe surfaced.
Show the answer

It broke down as disputes over Germany and Eastern Europe surfaced.

Beating Germany had held them together. Without a shared enemy, arguments over reparations and free elections grew into mistrust.

Beating Germany held the Allies together; once it was defeated, their disputes over Germany and Eastern Europe came to the surface.

The USA, Britain and USSR worked together to beat Germany. They did not agree on how the world should run. Soviet leader Joseph Stalin was also angry that the West took so long to open a major front against Germany.

At the Yalta and Potsdam conferences in 1945, leaders planned the peace. Hard questions stayed open. How much should Germany pay in reparations, or compensation? Could Eastern Europeans freely choose their governments? Rebuilding Germany could help Europe recover, but it could also revive a country the USSR feared.

Soviet-backed communists took control in Eastern Europe and silenced opponents. The West said this broke promises that freed peoples could choose their future. Soviet leaders, in turn, distrusted Western plans for Germany and feared losing control of neighbouring states. On 5 March 1946, Winston Churchill spoke of an Iron Curtain across Europe. It was an image for division, not a real wall. His speech described a split that already existed.

Yalta and Potsdam, 1945
Conferences to plan the postwar settlement.
Reparations
Payments for war damage.
Iron Curtain, March 1946
Churchill's image for Europe's division.

Real examples to use

Yalta, February 1945

Roosevelt, Churchill and Stalin agreed to divide Germany into zones and promised free elections in liberated Europe, but did not settle how they would be held.

Potsdam, July to August 1945

Truman, Attlee and Stalin quarrelled over Germany's reparations and Poland's new borders, showing the alliance cracking.

Worked example: Why old differences mattered more after victory

The USA and USSR had different systems during the war. Why did cooperation get harder after it?

  1. During the war, both needed to beat Germany, so they cooperated.
  2. After victory, they disagreed about Germany and Eastern Europe.
  3. With the common enemy gone, these disputes took over.

Watch out for this

Churchill's Iron Curtain speech created the division of Europe.

The speech described a division that already existed. It did not create it.

Check your understanding

Why did the alliance break down after 1945?

  1. They had settled their disputes at Yalta, so the break came from new leaders.
  2. Their shared enemy was gone, and disputes over Germany and Eastern Europe grew.
  3. Churchill's Iron Curtain speech ordered a real wall built across Europe, which the USSR resented.
Show the answer

Their shared enemy was gone, and disputes over Germany and Eastern Europe grew.

Yes. The reason to cooperate had disappeared.

Sources and context

Background reading for this chapter.

  • National Archives: Truman Doctrine

    Paraphrase of President Harry S. Truman's address to Congress, 12 March 1947; US National Archives transcript.

  • George C. Marshall Foundation: Harvard speech

    Paraphrase of Secretary of State George C. Marshall's Harvard speech, 5 June 1947; transcript held by the George C. Marshall Foundation.

  • Novikov telegram, University of Oregon primary-text transcription

    Paraphrase of Nikolai Novikov's telegram from Washington to the Soviet leadership, 27 September 1946, opening sections; English text hosted by the University of Oregon.

  • George C. Marshall Foundation: Harvard speech

    An original cartoon drawn for these notes in the style of a Soviet magazine cartoon of late 1947, after the USSR refused Marshall aid and made its Eastern European allies refuse it too. It is not a copy of a real cartoon.

  • Truman addresses Congress, March 1947

    Extract from President Harry Truman's address to a joint session of Congress, 12 March 1947, asking for aid for Greece and Turkey (the Truman Doctrine). A US government document in the public domain; text from the Avalon Project.

  • the British Foreign Secretary reports Molotov's warning, July 1947

    Extract from British Foreign Secretary Ernest Bevin's report of the final meeting of the British, French and Soviet foreign ministers in Paris on the Marshall Plan, 2 July 1947, sent to the US Secretary of State through the US Ambassador in London, 3 July 1947. Foreign Relations of the United States, 1947, volume III, document 180. A US government publication in the public domain.

  • the Cominform declaration, October 1947

    Extract from a telegram from the US Charge d'Affaires in Moscow, Elbridge Durbrow, to the Secretary of State, 6 October 1947, quoting the declaration issued when the Soviet Union and other communist parties set up the Cominform. Foreign Relations of the United States, 1947, volume IV, document 412. A US government document in the public domain.

  • the North Atlantic Treaty, April 1949

    Extract from Article 5 of the North Atlantic Treaty, signed in Washington on 4 April 1949 by the USA, Canada and ten Western European states, during the Berlin Blockade. Text from the Avalon Project.

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