Co-operation ends and the Cold War begins

The Yalta and Potsdam Conferences

Yalta Conference (February 1945): Roosevelt, Churchill and Stalin met to discuss the end of World War II, with their main discussion being about the division of Germany and reparations.
Potsdam Conference (July 1945): Truman replaced Roosevelt, and Attlee replaced Churchill, their main discussions involved disagreements over free elections in Eastern Europe and Truman’s revelation of the US atomic bomb.

Zones of Occupation: The Allies divided Germany into four zones of occupation (British, American, French and Soviet).
Berlin: Similarly, Berlin was also divided into four sectors. As the city lay in the Soviet zone, this caused significant tensions later.
Differences in austerity: The western zones began to prosper while the Soviet zone underwent severe austerity, sparking the beginnings of the Cold War tensions.

Iron Curtain: Stalin installed pro-Communist governments in Eastern Europe, creating what Churchill referred to as an ‘Iron Curtain’ dividing Europe into East and West.
Truman Doctrine (1947): The USA pledged to help any country threatened by Communism. This marked the start of the policy of ‘Containment’.
Marshall Plan (1947): The US offered financial aid to war-torn European countries, but Stalin refused to allow Eastern Bloc countries to accept it.

Berlin Blockade (1948): The Soviets blocked all routes into West Berlin in an attempt to gain control over the entire city.
Berlin Airlift (1948-1949): In response, the Western Allies airlifted supplies into West Berlin, showcasing their determination to resist Soviet expansionism.
Outcome: The Soviet Union lifted the blockade in May 1949, but the incident increased tensions and led to the formation of NATO (North Atlantic Treaty Organisation) by the Western powers.

NATO: Founding members included the USA, UK, France, and Canada among others. The Alliance was a collective security agreement against Soviet aggression.
Warsaw Pact (1955): In response to West Germany joining NATO, the Soviet Union formed the Warsaw Pact with other Communist states in Eastern Europe. This marked the official division of Europe into two military blocks.