Explain the origins of the Cold War, including the wartime conferences, the Iron Curtain, containment doctrine, and the Berlin Blockade.
Even before World War II ended, the wartime allies' unity was fraying. At the Yalta (February 1945) and Potsdam (July-August 1945) conferences, the United States, Britain, and the Soviet Union planned postwar Europe together, but mutual suspicion grew quickly as Stalin broke promises of free elections in Eastern Europe, instead installing loyal communist governments in Poland, Hungary, and elsewhere. In March 1946, Winston Churchill gave a name to the growing divide in a speech at Fulton, Missouri, warning that an "iron curtain" had descended across the continent, separating the communist East from the democratic West.
The United States responded with a strategy of containment: diplomat George Kennan's 1946 "Long Telegram" argued for resisting Soviet expansion firmly without provoking direct war, a strategy put into action through the Truman Doctrine (1947), which pledged US support to "free peoples" resisting subjugation and sent aid to Greece and Turkey, and the Marshall Plan (1948), which poured massive economic aid into rebuilding Western Europe, partly to make communism less appealing to struggling, war-torn populations. Tensions turned into direct crisis in 1948-1949, when the Soviet Union blockaded all land access to democratic West Berlin, deep inside Soviet-controlled East Germany; rather than abandon the city, the Western Allies flew in supplies for nearly a year in the Berlin Airlift until the Soviets finally lifted the blockade -- a crisis resolved through resolve and logistics rather than combat. By 1949, these tensions had hardened into formal structures: the United States and its allies formed the NATO military alliance (matched in 1955 by the Soviet-led Warsaw Pact), and Germany itself formally split into a democratic West and a communist East.
Mastery looks like: They can explain containment doctrine's core idea, trace how the Truman Doctrine and Marshall Plan put it into practice, and describe how the Berlin Airlift resolved a crisis without direct war.
Common stumbles: Treating the Cold War as starting with a single clear declaration, rather than recognizing how wartime allies' cooperation gradually eroded into open rivalry through specific broken promises and crises.