O Level World History: The Twentieth Century, 1919-1989 — Revision Notes (Cambridge 2147)

Related: Option B study guide

Condensed, exam-focused notes for Core Content Option B of Cambridge O Level World History (2147), 2024-2026 series. Use alongside the full study guide for worked examples and context.

2.1 Was the Treaty of Versailles fair?

• The “Big Three”: Wilson (USA) wanted a moderate peace based on his Fourteen Points; Lloyd George (Britain) wanted a settlement firm enough for British opinion but not crippling for Germany; Clemenceau (France) wanted Germany permanently weakened for French security.
• Terms imposed on Germany: loss of territory (Alsace-Lorraine, colonies), military restriction (army capped at 100,000, no air force, limited navy), reparations, and the war-guilt clause (Article 231).
• Fair or unfair: judged reasonable given the destruction of WWI, or harsh and short-sighted, fuelling German resentment that later fed Nazi propaganda.

2.2 Was the League of Nations a success?

• Aims: collective security, disarmament, improving working/living conditions internationally.
• Successes: settled some minor territorial disputes; ran useful technical work on health, refugees and labour standards.
• Failures: could not stop Japan’s invasion of Manchuria (1931) or Italy’s invasion of Abyssinia (1935-36); had no army of its own and depended on member states to act.
• Structural weakness: the USA never joined; major powers left or ignored its rulings once challenged.

2.3 Was Hitler’s foreign policy to blame for war in 1939?

• Hitler’s actions: remilitarising the Rhineland (1936), Anschluss with Austria (1938), the Sudetenland crisis (1938), invasion of the rest of Czechoslovakia, then Poland (1939).
• Weigh against other causes: appeasement by Britain and France (encouraged further aggression), the League’s demonstrated weakness (removed a check on Hitler), and the general collapse of collective security through the 1930s.
• Exam approach: never treat Hitler’s foreign policy alone — the syllabus explicitly expects a weighed judgement against these other factors.

2.4 Who was to blame for the Cold War?

• Wartime alliance (USSR + Western powers) broke down after 1945 over Eastern Europe’s and Germany’s future.
• Competing explanations: traditional view blames Soviet expansionism; revisionist view blames US economic and nuclear pressure; post-revisionist view sees mutual misunderstanding and mistrust on both sides.
• Key flashpoints to know: Yalta and Potsdam conferences, the Iron Curtain, the Truman Doctrine, the Marshall Plan, the Berlin Blockade/Airlift.

2.5 How effectively did the US contain communism?

• Truman Doctrine (1947): pledged support to countries resisting communism.
• Marshall Plan (1947): economic aid to rebuild Western Europe, reducing communism’s appeal.
• Later interventions assessed for effectiveness varied by region and period — success in some contexts (Western Europe’s economic recovery), more contested outcomes elsewhere.

2.6 How secure was Soviet control over Eastern Europe, 1948-c.1989?

• Methods of control: political (puppet communist governments), military (Warsaw Pact, direct intervention), economic (Comecon).
• Challenges to control: Hungary 1956, Czechoslovakia 1968 (Prague Spring), Poland’s Solidarity movement in the 1980s — each shows growing cracks in Soviet control before its collapse around 1989.

Exam technique for this option

Every question is framed as a judgement (“how far”, “to what extent”, “who was to blame”) rather than a request for narrative. Structure every answer as: state a clear judgement, support it with specific evidence, then explicitly weigh at least one counter-factor before confirming or refining the judgement in a concluding sentence. A chronological retelling of events without this weighing structure will not access the higher mark bands even if every fact stated is accurate. Build one timeline linking all six enquiries (2.1-2.6) together, since Versailles’ resentment feeds Hitler’s foreign policy, and the alliance that defeats Hitler is the same alliance that breaks down into Cold War — the six enquiries are a connected chain, not six isolated topics, and answers that show this connection score more highly than answers that treat each enquiry as a standalone unit of knowledge.

Linking source work to contextual knowledge

Although Option B is examined through Paper 1 (structured questions), candidates should not assume this means source evaluation is irrelevant — Paper 1 questions frequently present a short source extract or attributed viewpoint (for example, a quotation attributed to a historian debating who caused the Cold War) and ask candidates to use it alongside their own contextual knowledge, not to treat the source in isolation. A strong response identifies what the source actually claims, links it to the relevant contextual knowledge from the six enquiries above, and reaches a judgement that draws on both — never just paraphrasing the source without adding independent knowledge, and never ignoring the source entirely in favour of a pre-prepared answer that would work regardless of what the source said.

Building a “for and against” table for revision

For each of the six judgement-style enquiries in this option, build a simple two-column revision table listing the strongest evidence “for” one conclusion against the strongest evidence “for” the opposing conclusion, then practise writing the single sentence that weighs the two sides against each other. This habit — deliberately generating and weighing a counter-argument before reaching a conclusion — is the single most reliable way to convert accurate factual knowledge into the higher mark bands this option rewards, since examiners consistently report that candidates who know the facts but never explicitly weigh them against an alternative view underperform relative to their actual knowledge.

Self-test

1. Name the three “Big Three” negotiators at Versailles and one aim of each.
2. Give one League of Nations success and one structural weakness.
3. Besides Hitler’s foreign policy, name two other causes of WWII the syllabus expects you to weigh.
4. What were the Truman Doctrine and Marshall Plan designed to achieve?
5. Name two events showing challenges to Soviet control over Eastern Europe.

Answers: 1. Wilson (moderate peace/Fourteen Points), Lloyd George (firm but not crippling), Clemenceau (permanently weaken Germany). 2. Success: settled minor disputes/technical cooperation. Weakness: no army/USA never joined. 3. Appeasement, the League’s weakness/collapse of collective security. 4. Contain the spread of communism by pledging support and rebuilding Western European economies. 5. Hungary 1956, Czechoslovakia 1968, Poland’s Solidarity movement.