Origins of the Cold War: the breakdown of the wartime alliance, the Truman Doctrine, the Marshall Plan and the Berlin Blockade for N(A)-Level Humanities (History elective)
A module overview of how the Cold War began for Singapore N(A)-Level Humanities (History elective). Why the wartime alliance between the United States and the Soviet Union broke down after 1945, how the Truman Doctrine and Marshall Plan aimed to contain communism, and how the Berlin Blockade and Airlift became the first great crisis of the Cold War.
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Why this module matters
The Cold War shaped the world for nearly half a century, and this module explains how it began. It matters because the suspicion, the rival policies and the division of Europe set up everything in the later Cold War modules, from Korea and Cuba to the fall of the Berlin Wall. The skill it builds is explaining how a breakdown of trust turned former allies into bitter rivals.
This guide ties together the module's dot points, each with its own worked detail and practice. See the subject hub at /sg-n-level/history and the full syllabus list at /sg-n-level/history/syllabus.
The breakdown of the wartime alliance
The United States and the Soviet Union had united to defeat Hitler, but once the common enemy was gone their deep differences returned. They had opposite systems and distrusted each other, and they clashed over the future of Germany and Eastern Europe, where Stalin installed communist governments while the West wanted free elections. Work through the detail at the breakdown of the wartime alliance.
The American response: Truman Doctrine and Marshall Plan
The United States responded with two linked policies. The Truman Doctrine of 1947 promised to help free peoples resist communism, beginning with Greece and Turkey, and marked the start of containment. The Marshall Plan of 1948 offered huge economic aid to rebuild Europe, on the idea that prosperous countries would resist communism. See the Truman Doctrine and Marshall Plan.
The first crisis: the Berlin Blockade and Airlift
In 1948 Stalin blockaded West Berlin to try to force the Western powers out. They answered with the Berlin Airlift, flying in supplies for almost a year until Stalin gave up in 1949. It was the first great crisis of the Cold War and a clear Western success that deepened the division of Germany. Study the Berlin Blockade and Airlift.
Check your knowledge
Try these under timed conditions, then test yourself with the module quiz.
- Explain two reasons the wartime alliance broke down after 1945. (4 marks)
- State what is meant by the policy of containment. (2 marks)
- Explain the aim of the Truman Doctrine. (3 marks)
- Explain how the Marshall Plan was meant to stop the spread of communism. (3 marks)
- Explain why the Berlin Airlift was a success for the West. (3 marks)
Sources & how we know this
- Singapore-Cambridge GCE Normal (Academic) Level Humanities (Social Studies, History) Syllabus 2126 — Singapore Examinations and Assessment Board (2026)