Overview
In 1945 the “Big Three” had defeated Nazi Germany together. Within four years Europe was divided by an iron curtain Key term · 1946–1989 Iron Curtain Churchill's image for the division of Europe between Soviet-controlled Eastern Europe and the West. Why it matters It became the defining metaphor of the Cold War in Europe; the physical border fortifications fell in 1989. See in glossary → , Germany was split into two states, and the United States had signed its first peacetime alliance, NATO Key term · from April 1949 NATO The North Atlantic Treaty Organization, a military alliance of the USA, Canada and Western European states, pledging that an attack on one is an attack on all. Why it matters It committed the United States to Europe's defence in peacetime. The Soviet bloc responded with the Warsaw Pact in 1955. See in glossary → . This topic explains how mistrust, ideology and competing security needs turned allies into rivals.
Key dates
- Feb 1945 The Yalta Conference Key term · February 1945 Yalta Conference The meeting of Roosevelt, Churchill and Stalin that agreed to divide Germany into zones, to hold free elections in liberated Eastern Europe, and that the USSR would join the war against Japan. Why it matters Different interpretations of its promises — especially on Poland — fuelled mistrust once the war ended. See in glossary → .
- Jul–Aug 1945 The Potsdam Conference Key term · July–August 1945 Potsdam Conference The last wartime conference, with Truman and (from mid-conference) Attlee replacing Roosevelt and Churchill. It settled Germany's occupation and Poland's new western border. Why it matters Disputes over reparations and Poland, and Truman's hint about a powerful new weapon, showed the alliance fraying. See in glossary → ; the US uses atomic bombs on Japan.
- Feb 1946 George Kennan sends the Long Telegram Key term · 22 February 1946 Long Telegram George Kennan's cable from Moscow arguing that Soviet hostility sprang from insecurity and ideology and could be resisted with patient, firm pressure. Why it matters It gave Washington an intellectual basis for containment and influenced the shift to a harder line towards the USSR. See in glossary → .
- Mar 1946 Churchill’s “iron curtain” speech at Fulton, Missouri.
- Mar 1947 The Truman Doctrine Key term · 12 March 1947 Truman Doctrine President Truman's promise to support "free peoples" resisting subversion or outside pressure, first applied as aid to Greece and Turkey. Why it matters It turned containment into public policy and framed the Cold War as a global ideological struggle. See in glossary → .
- Jun 1947 The Marshall Plan Key term · 1947–1952 Marshall Plan The European Recovery Program, which gave about $13 billion in US aid to rebuild Western Europe's economies. Why it matters It helped Western Europe recover and tied it to the US, but Stalin's refusal to let Eastern Europe take part deepened the division of the continent. See in glossary → is proposed; Stalin forbids Eastern Europe to take part.
- Sep 1947 The USSR founds the Cominform Key term · 1947–1956 Cominform The Communist Information Bureau, set up by the USSR to coordinate the communist parties of Europe. Why it matters It was Stalin's answer to the Marshall Plan and a tool for enforcing Soviet control over Eastern European parties — Yugoslavia was expelled in 1948. See in glossary → .
- Feb 1948 Communists take power in Czechoslovakia.
- Jun 1948–May 1949 The Berlin Blockade Key term · June 1948 – May 1949 Berlin Blockade The Soviet closure of road, rail and canal routes to West Berlin, answered by an Anglo-American airlift that supplied the city for eleven months. Why it matters The first major crisis of the Cold War. Its failure hastened NATO and the division of Germany. See in glossary → and airlift.
- Apr 1949 NATO is founded.
- Aug–Oct 1949 The USSR tests an atomic bomb; two German states are created.
The breakdown of the alliance
Ideology. Capitalist democracy and Soviet communism each saw the other as a long-term threat.
Security. After two invasions from the West, Stalin wanted friendly governments in Eastern Europe and a weak Germany. To the West, Soviet control of Poland and the rest of Eastern Europe broke the promise of free elections made at Yalta.
Germany. The allies disagreed over reparations and Germany’s future. The Western zones were merged and revived economically; the Soviets stripped their zone of industry.
The atomic bomb. The US monopoly until 1949 deepened Soviet suspicion.
From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the Continent.
Why this quote matters
Churchill spoke as a private citizen but with President Truman on the platform. Stalin compared the speech to Hitler's racial theories. It publicly named the division of Europe and called for Anglo-American partnership against Soviet expansion.
Containment
George Kennan, a US diplomat in Moscow, argued that Soviet behaviour was driven by insecurity and ideology and could be resisted patiently without war. His ideas became the basis of containment Key term · from 1947 Containment The US policy of preventing the further spread of Soviet influence and communism through economic aid, alliances and, when necessary, military force. Why it matters It shaped US foreign policy for four decades, from the Truman Doctrine and Marshall Plan to the wars in Korea and Vietnam. See in glossary → .
I believe that it must be the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.
Why this quote matters
Truman asked Congress for aid to Greece and Turkey, but framed it as a universal commitment. The speech turned containment into public policy and presented the world as divided between free and totalitarian ways of life.
The Marshall Plan followed: billions of dollars of economic aid to rebuild Western Europe and make communism less attractive. Stalin saw it as dollar imperialism, founded the Cominform, and tightened his grip on Eastern Europe.
Berlin, 1948–1949
When the Western powers introduced a new currency, the Deutsche Mark, in their zones, Stalin cut all land routes to West Berlin. The United States and Britain supplied the city by air for eleven months. Stalin lifted the blockade in May 1949 — a propaganda defeat that accelerated the creation of NATO and of two German states.
Historians’ debate
The orthodox view, dominant in the West in the 1940s and 1950s, blamed Soviet expansionism and saw US policy as a necessary response.
Williams argued that the US pursuit of an “Open Door” for American trade and investment drove its policy and provoked Soviet fears.
Gaddis first stressed mutual misperception and shared responsibility; after Soviet archives opened, he placed renewed emphasis on Stalin’s personality and ideology.
Test yourself
Why did Poland become a source of conflict between the allies? Reveal
Britain had gone to war over Poland and the West wanted free elections there, as promised at Yalta. Stalin saw a friendly Poland as essential to Soviet security and imposed a communist-dominated government.
How were the Truman Doctrine and the Marshall Plan linked? Reveal
Both put containment into practice: the Truman Doctrine promised political and military support to countries resisting communism, and the Marshall Plan provided the economic aid to rebuild Europe so that communism would be less attractive.
What were the consequences of the Berlin Blockade? Reveal
It was a Soviet propaganda defeat; it hastened the creation of NATO (April 1949) and the division of Germany into the Federal Republic and the German Democratic Republic; and it confirmed Berlin as a Cold War flashpoint.
Key terms
- Berlin Blockade June 1948 – May 1949
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The Soviet closure of road, rail and canal routes to West Berlin, answered by an Anglo-American airlift that supplied the city for eleven months.
Significance: The first major crisis of the Cold War. Its failure hastened NATO and the division of Germany.
- Cominform 1947–1956
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The Communist Information Bureau, set up by the USSR to coordinate the communist parties of Europe.
Significance: It was Stalin's answer to the Marshall Plan and a tool for enforcing Soviet control over Eastern European parties — Yugoslavia was expelled in 1948.
- Containment from 1947
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The US policy of preventing the further spread of Soviet influence and communism through economic aid, alliances and, when necessary, military force.
Significance: It shaped US foreign policy for four decades, from the Truman Doctrine and Marshall Plan to the wars in Korea and Vietnam.
- Iron Curtain 1946–1989
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Churchill's image for the division of Europe between Soviet-controlled Eastern Europe and the West.
Significance: It became the defining metaphor of the Cold War in Europe; the physical border fortifications fell in 1989.
- Long Telegram 22 February 1946
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George Kennan's cable from Moscow arguing that Soviet hostility sprang from insecurity and ideology and could be resisted with patient, firm pressure.
Significance: It gave Washington an intellectual basis for containment and influenced the shift to a harder line towards the USSR.
- Marshall Plan 1947–1952
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The European Recovery Program, which gave about $13 billion in US aid to rebuild Western Europe's economies.
Significance: It helped Western Europe recover and tied it to the US, but Stalin's refusal to let Eastern Europe take part deepened the division of the continent.
- NATO from April 1949
-
The North Atlantic Treaty Organization, a military alliance of the USA, Canada and Western European states, pledging that an attack on one is an attack on all.
Significance: It committed the United States to Europe's defence in peacetime. The Soviet bloc responded with the Warsaw Pact in 1955.
- Potsdam Conference July–August 1945
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The last wartime conference, with Truman and (from mid-conference) Attlee replacing Roosevelt and Churchill. It settled Germany's occupation and Poland's new western border.
Significance: Disputes over reparations and Poland, and Truman's hint about a powerful new weapon, showed the alliance fraying.
- Truman Doctrine 12 March 1947
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President Truman's promise to support "free peoples" resisting subversion or outside pressure, first applied as aid to Greece and Turkey.
Significance: It turned containment into public policy and framed the Cold War as a global ideological struggle.
- Yalta Conference February 1945
-
The meeting of Roosevelt, Churchill and Stalin that agreed to divide Germany into zones, to hold free elections in liberated Eastern Europe, and that the USSR would join the war against Japan.
Significance: Different interpretations of its promises — especially on Poland — fuelled mistrust once the war ended.