Who was to blame for the Cold War?

Cambridge IGCSE History 0470 · Paper 1 Section A, Core Content Option B Syllabus: 2027 and 2028 Option B: The twentieth century: international relations since 1919 Key Question 4 of six

This file covers the origins of the Cold War: why the wartime alliance broke apart between 1945 and 1949, how the USSR came to control Eastern Europe by 1948, how the United States answered, what the Berlin Blockade settled, and how to argue about who was more to blame.

If you are looking for Korea, Cuba or Vietnam, you want Key Question 5, How effectively did the United States contain the spread of communism? If you are looking for Hungary 1956, the Berlin Wall, the Prague Spring, Solidarity or Gorbachev, you want Key Question 6, How secure was the USSR's control over Eastern Europe, 1948 to c.1989? Section 3 shows exactly where Cambridge draws those two lines, because they matter more here than anywhere else on the course.

One thing to hold onto before anything else. This Key Question is two-sided by construction. Cambridge wrote a fifth focus point that names both superpowers and asks which was more to blame. A file that blames one of them, and a candidate who does the same, cannot reach the top band. Everything below is arranged so that both cases arrive with real material attached.

1. What the syllabus actually asks

This is the wording printed in the Cambridge IGCSE History 0470 syllabus for 2027 and 2028, on the Option B content page.

Key Question 4

Who was to blame for the Cold War?

Focus points

• Why did the US-Soviet alliance begin to break down in 1945?
• How had the USSR gained control of Eastern Europe by 1948?
• How did the United States react to Soviet expansionism?
• What were the consequences of the Berlin Blockade?
• Who was more to blame for starting the Cold War: the United States or the USSR?

Specified content

• The origins of the Cold War:
• the 1945 summit conferences and the breakdown of the US-Soviet alliance in 1945-46
• Soviet expansion into Eastern Europe to 1948, and American reactions to it
• the occupation of Germany and the Berlin Blockade
• NATO and the Warsaw Pact

Read the focus points as arguments, not as a checklist

Cambridge states in its own introduction to the subject content that focus points identify the issues that enable candidates to gain an understanding of the key question. That is a strong hint. Each focus point is effectively a ready made 10 mark essay title, and four of the five have been set almost word for word on real papers.

A note on the syllabus wording

Cambridge prints the Option B title two ways in the same document. The contents page and the subject content introduction both call it The twentieth century: international relations since 1919. The header on the Option B content page reads from 1919. They mean the same thing. Use "since 1919".

Note also that Cambridge sets the dashes in "US-Soviet" and "1945-46" as en dashes in the PDF. They are printed here as ordinary hyphens for readability on screen. The words are unchanged.

2. Where this Key Question turns up on the papers

The marking ladders are the same for every question on Paper 1, and they are set out in the How Cambridge marks History 0470 Paper 1 notes: the three parts and their marks, the assessment objective split, the level descriptors, and the two rules Cambridge changed for the 2024 series. Read that page once. Nothing below repeats it.

What is specific to this Key Question is where it appears and how often.

It is Question 7, and it is very consistent

Of the 48 Paper 1 mark schemes read for these notes, covering March, June and November from 2018 to 2024, 25 set a question on this Key Question. Every single one of those 25 was Question 7. Not one appeared at 5, 6 or 8.

That is a little over half of all papers in seven years, which makes this one of the two or three most heavily examined topics in Option B. One Principal Examiner report describes it as the second most popular question in Section A that series.

Two cautions before you build a revision plan on the number 7.

The question pool has changed. The papers in that corpus were set on an older version of the syllabus, which had a seventh key question in Option B on Iran and Iraq. Question 8 was usually that topic. The 2027 and 2028 syllabus has only six key questions and no Gulf content at all, so the four Option B questions are now drawn from a smaller pool. The number 7 may not hold.

The split rule does hold, and it is printed. The syllabus states that Section A contains eight questions, four from Option A and four from Option B, and that in each option two questions will be set from key questions 1 to 3 and two questions will be set from key questions 4 to 6. This Key Question sits in the second group with containment and Eastern Europe. Revising only the Versailles and League half of Option B leaves you choosing between two questions instead of four.

It is also a Paper 2 topic in 2028

The syllabus prints the prescribed topics for Paper 2. For examination in 2028, Who was to blame for the Cold War? is the Option B prescribed topic for both the March exam (India only) and the November exam. It is not a prescribed topic in 2027.

That matters, but not in the way most students assume. Paper 1 carries no source marks at all. The same knowledge earns marks on both papers, but the skills are different, and how Paper 2 uses sources is a separate matter entirely.

3. Where Cambridge draws the line with Key Questions 5 and 6

These three overlap more than any other trio in the course, and examiner reports name the confusion every year. The syllabus wording settles it.

The line with Key Question 6 is the year 1948

Your focus point asks how the USSR had gained control of Eastern Europe by 1948, and your specified content says Soviet expansion into Eastern Europe to 1948. Key Question 6 is titled How secure was the USSR's control over Eastern Europe, 1948 to c.1989?

So the taking is yours. The keeping belongs to Key Question 6. Poland 1945 to 1947, Czechoslovakia 1945 to 1948, the rigged elections, Cominform: yours. Hungary 1956, the Prague Spring 1968, Solidarity, Gorbachev: not yours.

Berlin is split down the middle by twelve years

Your specified content names the occupation of Germany and the Berlin Blockade, which is 1948 to 1949. Key Question 6's specified content names the Berlin Wall, which is 1961.

This is the single most examiner-flagged error on the whole topic. Reports from at least five separate series record candidates writing about the Wall when asked about the Blockade or the Airlift, and reports also record candidates muddling East and West Berlin. Blockade and Airlift are 1948 to 1949 and belong here. The Wall is 1961 and belongs to Key Question 6.

Containment sits on the boundary, and Cambridge uses it on both sides

Key Question 5 is titled How effectively did the United States contain the spread of communism?, so containment in practice is that file's business. But Cambridge has set the part (a) question "What was the policy of 'containment'?" twice in the corpus read here, and each time attached it to a different Key Question. In one paper it sits with the Greek Civil War and the Berlin Blockade, which is squarely yours. In another it sits with Cuba and Vietnam, which is Key Question 5.

The working rule: the Truman Doctrine as the origin of containment is yours; containment applied in Korea, Cuba and Vietnam is Key Question 5.

NATO and the Warsaw Pact are yours, but the question's dates outrank the syllabus

NATO (1949) and the Warsaw Pact (1955) are named in your specified content, and both have been set as part (a) and part (b) questions on Question 7. But a Principal Examiner report on a question that asked about Stalin's methods by 1948 notes that candidates who reached for Comecon and the Warsaw Pact were writing outside the specified timeframe and earned nothing for it.

Being in your specified content does not make something relevant to a question with a date limit in it. The date limit wins every time.

4. Focus point one: why the alliance broke down in 1945

The Grand Alliance was a marriage of necessity between a communist dictatorship and two capitalist democracies. The interesting historical question is not why it ended but why it lasted as long as it did. Cambridge sets this focus point most often as a part (b), and it wants reasons, not a narrative of the conferences.

Yalta, February 1945: agreement while Germany was still fighting

Cambridge's mark schemes credit these as decisions taken at Yalta:

• Germany would be divided into four zones: American, British, French and Soviet.
• Berlin would be divided the same way, in four zones.
• Germany would surrender unconditionally, be de-Nazified, and pay reparations, much of it going to the USSR.
• War criminals would be hunted down and tried.
• The United Nations would be set up.
• Eastern Europe would be a Soviet sphere of influence.
• Free elections would be held in countries liberated from German occupation.
• On Poland specifically: a provisional government, to be called the Polish Provisional Government of National Unity, combining the pro-Soviet Lublin Poles and the exiled London Poles; Poland's eastern border on the Curzon Line; the border moved westwards into German territory; free, multi-party elections.

Notice how much of that is genuine agreement. A candidate who claims the two sides never agreed on anything is contradicted by Cambridge's own indicative content.

Potsdam, July 1945: the same table, different people, different situation

By Potsdam three things had changed. Roosevelt had died and Truman had replaced him. Attlee replaced Churchill during the conference. One examiner report puts it neatly: Stalin was the only survivor of Yalta. And, as Cambridge's own mark scheme notes, by July 1945 Soviet troops had taken over eastern Europe, so what had been a promise at Yalta was now a fact on the ground.

1. Roosevelt dies
2. Truman arrives at Potsdam distrusting Stalin and inexperienced in foreign affairs
3. the leader who made the Yalta bargain is gone from the American side
4. the conference that had to settle Germany opens with less trust than the one that settled less

Cambridge credits these as agreements at Potsdam: Germany and Berlin divided as agreed at Yalta; de-Nazification; war crimes trials; the Nazi Party banned; the German and Polish border settled at the Oder-Neisse Line; Germany governed by an Allied Control Council based in Berlin; all of Germany to have the same currency and be treated as one economic unit; each power to take reparations from its own zone; Germans living in Poland, Hungary and Czechoslovakia to be sent back to Germany. One mark scheme opens its list with the flat sentence "Little was agreed at Potsdam", which tells you how Cambridge reads the balance.

And these as disagreements: elections in Poland; what to do with Germany, with Stalin wanting it crippled and the West wanting it to recover; access to Germany's industrial heartland; reparations; recognition of the East European countries; the USSR's demand for a role in occupied Japan.

The atomic bomb, and a trap examiners flag by name

The Americans tested an atomic bomb in July 1945 and Truman told Stalin about it at Potsdam. Cambridge's mark schemes treat Truman's secrecy about the programme as a genuine cause of Soviet suspicion: one prints the reasoning that Stalin "interpreted this secrecy to mean that the USA would use the bomb to win worldwide power."

The trap: a Principal Examiner report records as a common misconception the claim that Truman told Stalin at Potsdam that he had dropped the bomb on Hiroshima. Hiroshima came after the conference. Get the sequence right or the point collapses.

A second, subtler trap from the same family of reports. One report on a part (a) asking for disagreements at Potsdam notes that Roosevelt's death, Attlee's arrival and Truman's dislike of communism "may have contributed to the atmosphere but were not specific subjects of dispute at Potsdam." Atmosphere is not a disagreement. Reparations, Poland, Germany and de-Nazification are.

What else Cambridge credits for the 1945 breakdown

From the mark schemes and reports: the ideological gulf between communism and capitalism; the collapse of trust as the common enemy disappeared; Britain and America's delay in opening a second front, which Stalin had wanted earlier; and the USSR's growing sphere of influence in Eastern Europe.

Churchill's Iron Curtain speech belongs here too. Cambridge dates it to 1946 and treats it as a cause of ill feeling in its own right. Stalin's reply in Pravda on 16 March 1946 compared Churchill to Hitler and defended Soviet policy as protection, not expansion.

5. Focus point two: how the USSR gained control of Eastern Europe by 1948

This focus point is asked as a part (a) more than any other on this Key Question, in various forms: describe how the communists took over Czechoslovakia between 1945 and 1948; describe how the Soviet Union consolidated its hold over Poland from 1945; what methods did Stalin use to gain control over Eastern European states by 1948. You need concrete method, not the general claim that Stalin took over.

The method, as Cambridge's mark schemes set it out

• The Red Army liberated Poland, Czechoslovakia, Hungary, Bulgaria and Romania from the Nazis and then stayed.
• A secret police was created immediately in each occupied country.
• Trusted communists were placed in charge of radio, the most powerful mass medium of the time.
• Communists took key posts inside coalition governments and then took over the rest.
• Rival parties were harassed, then banned. Political opponents were arrested, imprisoned or murdered.
• Elections were rigged.
• Cominform in 1947 and Comecon in 1949 bound the bloc politically and economically.

Examiner reports refer to this pattern by the name candidates gave it, salami tactics, and record it being used effectively.

Poland, the test case that broke the Yalta promise

Cambridge's own indicative content: Soviet troops did not go home after the war. The free elections agreed at Yalta did not happen; the 1947 election was rigged and the communists won a huge victory. Non-communist leaders were arrested or murdered. Poland was banned from accepting Marshall Aid, made to join Cominform in 1947, Comecon in 1949 and the Warsaw Pact in 1955.

Poland is also the clearest case for the Soviet defence, and you should give it both ways. One mark scheme prints the argument that security "would prevent Poland being used as a corridor for another German attack", and a source in a Cambridge Paper 2 adds the sting in the tail: it also "ensured that the same country could be used as a Russian corridor to the West."

Czechoslovakia, the case Cambridge treats as the turning point

The mark schemes give this sequence: Soviet troops withdrew in 1945; Beneš, who was not a communist, became President; elections in 1945 produced a coalition; in the 1946 elections the Communist Party was the largest single party; communists gradually took the key government posts; the party organised strikes and protests against its rivals; in 1947 Czechoslovakia was stopped from joining the Marshall Plan and forced into Cominform; in February 1948 the communists staged a coup and forced the other parties out; Jan Masaryk, the only non-communist left in the government, was killed in March 1948; rigged elections in May 1948 confirmed communist control; Beneš was ousted in June 1948 and Gottwald became President.

One Paper 2 source in Cambridge's own materials calls Czechoslovakia the last addition to the Soviet bloc, which is exactly why 1948 is the year the syllabus chooses as its boundary.

Two examiner-flagged errors specific to this content. Candidates repeatedly write about the Prague Spring of 1968 when the question says 1948, which is both the wrong decade and the wrong Key Question. And candidates repeatedly state that the Soviet army invaded in 1948. It did not. The 1948 takeover was a coup by the domestic Communist Party while the Red Army massed on the borders. The invasion is 1968.

Was it a plan or an improvisation? Give both

This is the best available material for the "case that neither side simply chose it" argument, and Cambridge supplies it in its own Paper 2 sources, which explicitly disagree with each other.

One source argues that even before the German invasion of 1941 Soviet authorities were preparing to impose their own system, that the Soviets imported the same three elements into every country the Red Army entered, and that the harsher policies of 1947 and 1948 were not merely a reaction to the Cold War.

Another argues the opposite emphasis: that Soviet control did not take place overnight and that much depended on local conditions. In Albania local communists established rule in 1944 to 1945 as patriots who had fought the Germans. In Poland the takeover needed heavy Soviet involvement. In Hungary Stalin held back until 1947. In Czechoslovakia a liberal democracy looked likely to survive until the coup.

A third, older source goes further still and argues that the Russians "had no intention of Sovietising Eastern Europe in 1945 if they could find alternatives", and points out that neither the Americans, the British nor the Russians allowed democracy to run its course anywhere in Europe at the cost of their own strategic interests.

You do not have to decide which is right. You do have to know that Cambridge itself presents this as contested, and a candidate who says so with evidence is arguing at the level the top band wants.

6. Focus point three: how the United States reacted to Soviet expansionism

The word reacted is doing real work in the focus point. Cambridge is asking about the sequence, and the sequence is the argument.

The Greek Civil War and the Truman Doctrine

Cambridge's own indicative content on Greece: two rival groups, monarchists and communists; the monarchists supported by Britain and the United States, the communists by the Soviet Union; civil war in Athens put down by the British; an election in 1946 and a plebiscite that restored the King; a communist uprising; the British pulled out in February 1947 because they could no longer afford it; the United States replaced them; the Truman Doctrine was put into action; massive American military and economic aid poured in; in 1949 the Greek army defeated the communists.

One Cambridge Paper 2 source dates the doctrine precisely: "On 12 March 1947, President Truman issued his own declaration of Cold War."

For part (a), Cambridge credits the Truman Doctrine as: an American policy of containment; the USA would help any country threatened by aggression; military and economic aid to Greece; to defend free peoples from communist aggression; to contain Soviet aggression. An examiner report notes the commonest mistake on this question was describing the Marshall Plan instead, and describing it wrongly, as finance offered to Eastern Europe.

The Marshall Plan, and why Cambridge treats its motive as genuinely open

George Marshall announced the plan in June 1947. Cambridge reproduces his speech, in which he says the policy "is not directed against any country or doctrine but against hunger, poverty, desperation and chaos." The money was offered to Western and Eastern Europe. The USSR refused and forbade its bloc to apply.

Cambridge's mark schemes are unusually even-handed here, and print reasons on both sides.

Why Western Europe welcomed it: industries destroyed by bombing and fighting; Britain out of money; millions in refugee camps; trade disrupted; recovery doubtful without aid; and, explicitly, because it helped stop communism spreading in their own countries.

Why the United States wanted it: to keep communism out of Europe; to gain economic control of western Europe; to make Europe dependent on the dollar; to create markets for American exports; to prevent a worldwide economic slump. Cambridge prints a Level 3 exemplar that puts the mechanism plainly: America needed to sell its goods, Europe could only buy them if its economy recovered, so rebuilding Europe built the market.

Why Stalin refused: he saw it as an American plot to destroy communism; recipients would have to bring their economies into line with the United States; it would weaken his control over Eastern Europe; it would make capitalism look superior. A Soviet speech to the United Nations in September 1947, reproduced by Cambridge, calls it "an attempt to split Europe into two camps" and objects to its use of Western Germany as a base for American expansion.

And Cambridge sets an American source arguing that the offer to the Soviets was never sincere, because the Americans made acceptance unlikely by demanding that each nation's economic records be opened for inspection. The same source quotes Truman saying the Truman Doctrine and the Marshall Plan "are two halves of the same walnut."

That last quotation is worth more than any date in this section. It is Cambridge putting an American admission into a candidate's hands that the aid and the containment policy were one project.

1. Marshall Aid offered to all of Europe including the East
2. Stalin forbids his bloc to apply
3. Cominform in 1947 and Comecon in 1949 bind the bloc instead
4. the division of Europe becomes formal, and each side can point at the other's move as the cause

An examiner-flagged error here: candidates who believe Marshall Aid was accepted by Eastern Europe, and candidates who confuse the Marshall Plan with containment as a policy. A second: candidates who answer "why did Western Europe welcome it" by writing at length about why Truman introduced it, which is a different question.

The Long Telegram and the Novikov telegram, mirror images

Cambridge reproduces both, and the pairing is the best short illustration of the mutual-misperception argument.

George Kennan, an American diplomat in Moscow, 22 February 1946: the USSR sees itself in a hostile "capitalist encirclement" with which there can be no peaceful coexistence; everything must be done to increase Soviet strength and to deepen the divisions between capitalist powers; Soviet success "will depend on the degree of firmness the Western world can muster."

Nikolai Novikov, Soviet ambassador in Washington, 27 September 1946: American foreign policy "is characterised by a striving for world domination"; all the forces of American diplomacy, the armed services, industry and science have been placed at the service of that policy; American preparations for a future war are conducted "with the idea of war against the Soviet Union."

Each government was being told, by its own most trusted observer in the other's capital, that the other side intended to dominate the world. Neither telegram is evidence that the other side actually did.

7. Focus point four: the consequences of the Berlin Blockade

Berlin was the point where the argument about Germany stopped being an argument. Cambridge examines it constantly, in all three parts, and the focus point asks specifically about consequences.

What happened, in the order Cambridge gives it

Berlin was divided into four zones but lay 100 miles inside the Soviet part of Germany. Cambridge's background information for a Paper 2 on the topic states this plainly and adds that it "made it easy for Stalin to blockade the Western sectors."

The sequence, from a source Cambridge set in 2024: on 1 June 1948 the Western Allies announced plans for a separate West German state; on 18 June a new currency was announced; on 23 June, in response, the Soviets issued their own currency for East Germany and cut the rail links; a total blockade followed on 23 to 24 June, cutting rail, road and water access and electricity supplies. The West responded with an airlift. The blockade ended in May 1949.

Why Stalin did it, and why it failed

Cambridge's mark schemes credit as reasons for the blockade: the western zones were being merged; a new currency had been introduced without informing Stalin; Marshall Aid was flowing into the western zones and West Berlin was flourishing; Stalin did not want Germany to recover; he wanted the western powers out of Berlin and did not want a symbol of capitalism sitting inside his zone. One Cambridge source is blunt: "Stalin's policy was not part of a larger planned move of aggression. Stalin's purpose was to force the West to leave the city or abandon its plans for a separate West German state."

Reasons for its failure, from the mark schemes: the airlift worked; Britain, France and the USA would not back down; the Soviets did not fire on Allied aircraft; Stalin would not risk escalating to war. One Cambridge source adds a mechanical reason that is worth a mark on its own: Stalin never obstructed Western access by air, which is what made the airlift possible at all.

The consequences, which is what the focus point actually asks for

Cambridge credits: the Western powers stayed in Berlin; Berlin stayed divided; Europe would be divided for over 40 years; Stalin's plan to take Berlin failed; the western zones were unified and West Germany was created; and the failure "proved that America was prepared to act on containment." Examiner reports add the propaganda dimension: a success for the Allies and a corresponding failure for Stalin, and the point that West Berlin now stood as a sign of freedom behind the Iron Curtain. One examiner report notes that the strongest answers also observed that Berlin was the international capital of espionage, so being forced out would have cost the West more than prestige.

1. Blockade fails
2. West Germany is founded and NATO is signed in 1949
3. the Warsaw Pact answers NATO in 1955
4. the argument about how to govern Germany hardens into two permanent military alliances

NATO and the Warsaw Pact

For part (a) on NATO, Cambridge credits: the North Atlantic Treaty Organisation; set up in 1949; a reaction to the Berlin Blockade; included Britain, France and the USA; collective security against the USSR; mutual defence.

For the Warsaw Pact, Cambridge is specific about the trigger and about a mistake. The Pact was formed in 1955, and the mark schemes credit it as a reaction to the formation of NATO in 1949 and, more precisely, to West Germany joining NATO and being allowed to rearm in May 1955. An examiner report records two common misconceptions: that the Warsaw Pact was set up by Stalin, who had died two years earlier, and that it was an instant reaction to NATO in 1949, which is six years out. Another report notes that most candidates could say the Pact answered NATO but could not explain why NATO threatened the communist states, which is the difference between Level 2 and Level 4 on a part (b).

8. Focus point five: who was more to blame

This is where the marks are, and it is the focus point Cambridge turns into part (c) most often. In the corpus read here, part (c) has been set as: who was more to blame, the USA or the USSR; was Truman to blame; were Stalin's actions between 1946 and 1949 responsible; were Stalin's policies in Eastern Europe defensive; how far was the Cold War caused by the USSR's need for security; was the Berlin Blockade defensive or aggressive; was it surprising that Britain and the USA conceded a Soviet sphere at Yalta; which did more damage, Poland or Marshall Aid; which was more of a threat, the Truman Doctrine or the Marshall Plan.

Every one of those is the same argument wearing a different hat. Learn the argument once.

The case against the USSR

Attributed as Cambridge's mark schemes and examiner reports present it, this is the case candidates make most readily.

• Stalin broke the Yalta agreement. Free elections were promised in liberated countries and did not happen. Poland is the standing example, with the rigged 1947 election.
• The takeovers used force and fraud, not consent. Opponents arrested and murdered; parties banned; elections rigged; Masaryk killed in March 1948.
• Communist ideology was expansionist. One mark scheme prints it as a Level 2 identification in almost those words: the ideology was intent on imposing its system of government throughout the world.
• Cominform and Comecon were instruments of control, and Cominform in particular was read in the West as a signal that Stalin meant to direct communist parties across the whole of Europe, including in France and Italy.
• The Berlin Blockade was a provocation, an attempt to starve two million civilians into changing which flag flew over their city.
• Stalin also wanted reparations and resources, not only security. Cambridge prints the argument that he stripped industrial plant from the Soviet zone of Germany and sent it east by train, which is an economic motive, not a defensive one.

The case against the USA

This side is thinner in most candidates' answers, which is exactly why it is worth more. Examiner reports repeatedly note that responses are stronger on one side than the other and that one-sided answers are capped.

• Truman's personal hostility. Cambridge's mark schemes credit Truman being strongly anti-communist, taking an aggressive line from the start, and being aggressive in his dealings with Soviet officials.
• The atomic bomb, and the secrecy about it. The United States kept the testing programme secret and then refused to share the technology. Cambridge prints the inference Stalin drew from that: that the USA meant to use the bomb to win worldwide power.
• The Truman Doctrine. By declaring that the United States would help any country threatened by communism, Truman committed America to opposing the USSR everywhere. One mark scheme puts it flatly: "This was bound to cause friction with the USSR."
• The Marshall Plan as dollar imperialism. Not merely that Stalin thought so, but that Cambridge itself sets sources and exemplars saying so: aid tied to opening a country's economic records, aid that created markets for American exports, aid that made Europe dependent on the dollar, aid that was half of the same walnut as containment.
• Breaking the Potsdam agreement over Germany. This one is under-used and it is strong. Potsdam agreed that Germany would be treated as one economic unit with one currency. Cambridge's own mark scheme prints, as a creditable point, that "the creation of Bizonia and the new currency in the western zones of Germany was in breach of the Potsdam Conference agreement." If breaking agreements is the charge against Stalin, the same charge is available against the West.
• Western intervention in the Russian Civil War. Cambridge credits Stalin's suspicion of the West as dating back to American and British intervention on the side of the Whites in 1917 and after, and to the Western willingness in the 1930s to see Hitler expand eastwards.

The case that neither side simply chose it

This is the argument that reaches Level 5 most reliably, because it does what "how far" asks. Cambridge supports it, and you can attribute every piece.

Both sides were being told the other intended world domination. The Long Telegram and the Novikov telegram, six months apart, say the same thing about opposite countries. Neither is evidence of the other's intentions; both are evidence of how each side read the other.

The same act was defensive to one side and aggressive to the other. Cambridge's mark schemes say this outright in their exemplars. On Eastern Europe: "For Stalin this was a defensive measure to prevent the Soviet Union being invaded again. For the West it was an aggressive move." On the Berlin Blockade, a 2024 mark scheme is even more explicit: "Stalin's move can be seen as aggressive and defensive at the same time."

Neither superpower was willing to let the other's system near it, and neither was unique in that. Cambridge sets a source arguing that the Russians showed "neither more nor less respect for democracy in Eastern Europe than the Americans and British showed in Italy, Greece or Belgium."

Historians have moved away from the blame question altogether. Cambridge reproduces a source saying that from the 1970s scholarship "began to move beyond the simple application of blame and responsibility" and started treating the Cold War as an interaction between all parties. That is a legitimate and creditable position, provided you attach evidence to it rather than using it to avoid having a view.

But do not stop at "both sides". A mark scheme prints the exact sentence that scores one mark: "Both the USSR and the USA contributed to the start of the Cold War." Saying it was mutual is a Level 1 generalisation. Showing it was mutual, with an act from each side and a mechanism, and then still saying which mattered more, is Level 5.

Judgement sentences that work on this topic

These are shapes, not scripts. Each states a position and attaches a reason, which is what the top mark asks for.

• "Stalin was more to blame for starting it, because it was his breach of the Yalta promise on elections that gave Truman the evidence a hard line needed."
• "The USA was more responsible for turning a dispute into a system, because the Truman Doctrine committed it to opposing communism everywhere, not just where the Red Army stood."
• "Neither side chose the Cold War, but the USSR chose the actions the West could not ignore, and being defensive is not the same as being blameless."
• "The blockade was defensive in motive and aggressive in effect, and effect is what the other side had to respond to."
• "Blame is the wrong shape of question, because each government acted on an assessment of the other that its own diplomats had already written and that neither could check."

9. The mistakes examiners name on this content

The faults that apply to any Paper 1 question are listed in the How Cambridge marks History 0470 Paper 1 notes. These are the ones the Principal Examiner reports name on this topic, series after series.

• Confusing the Berlin Blockade with the Berlin Wall. Named in at least five separate reports. Blockade 1948 to 1949; Wall 1961 and a different Key Question.
• Confusing East and West Berlin, including the belief that the airlift supplied East Berlin.
• Confusing Yalta with Potsdam. Named repeatedly, in both directions.
• Confusing Cominform with Comecon, and getting their dates and purposes the wrong way round. Cominform 1947, political. Comecon 1949, economic.
• Believing the Warsaw Pact was set up by Stalin, who died in 1953, or that it was an immediate answer to NATO in 1949 rather than to West German rearmament in 1955.
• Believing the Red Army invaded Czechoslovakia in 1948. The 1948 takeover was a coup. The invasion is 1968.
• Believing Truman told Stalin at Potsdam about Hiroshima. Hiroshima came after the conference.
• Writing about the Prague Spring when the question says 1948.
• Drifting forward into Vietnam and the Cuban Missile Crisis on a question about the origins of the Cold War. Named explicitly in more than one report as not relevant to this Key Question.
• Ignoring the date limit. Reports name candidates using the Warsaw Pact and Comecon on a question bounded "by 1948", Hungary 1956 and the Berlin Wall on a question bounded "1945 to 1949", and Solidarity in the 1980s on a question about Stalin's motives.
• Answering a neighbouring question. Asked why Western Europe welcomed the Marshall Plan, candidates explain why Truman introduced it. Asked why the Allies were determined to defeat the blockade, candidates explain why Stalin imposed it. Asked about the motives of Britain and the United States at Yalta, candidates explain Stalin's motives instead.
• Naming Bizonia and the new currency without saying they breached Potsdam. The fact on its own is a description. The breach is the argument.
• On the "same methods in Poland and Czechoslovakia" question, one report records that candidates wrote about how the USSR maintained control rather than how it took control. That is the 1948 line again, in miniature.

10. Quick revision

• Yalta, February 1945. Germany and Berlin into four zones; unconditional surrender; de-Nazification; reparations; war criminals tried; United Nations; Eastern Europe a Soviet sphere of influence; free elections in liberated countries; Poland to have a provisional government of Lublin and London Poles, the Curzon Line in the east, and multi-party elections.
• Potsdam, July 1945. Truman has replaced Roosevelt; Attlee replaces Churchill during the conference; Soviet troops already hold Eastern Europe; the atomic bomb has been tested. Agreed: Yalta's division confirmed, de-Nazification, war crimes trials, Nazi Party banned, Oder-Neisse Line, Allied Control Council, one currency and one economic unit, reparations from each power's own zone. Disagreed: Poland, reparations, whether Germany should recover, Japan.
• Iron Curtain speech 1946. Stalin's reply in Pravda, 16 March 1946, compared Churchill to Hitler.
• Long Telegram, Kennan, 22 February 1946. Novikov telegram, 27 September 1946. Mirror images.
• Truman Doctrine, 12 March 1947. Aid to any country threatened by communism. First applied in Greece, after Britain withdrew in February 1947; the communists were defeated in 1949.
• Marshall Plan, June 1947. Offered to all of Europe. Stalin forbade his bloc to apply.
• Cominform 1947, political. Comecon 1949, economic. Tito expelled from Cominform 1948.
• Czechoslovakia: coalition 1945; largest single party 1946; coup February 1948; Masaryk killed March 1948; rigged elections May 1948; Beneš out June 1948. The last addition to the Soviet bloc.
• Poland: troops stayed; 1947 election rigged; opponents arrested or murdered.
• Berlin Blockade. Berlin lay 100 miles inside the Soviet zone. Separate West German state announced 1 June 1948; new Western currency 18 June; Soviet currency and rail cuts 23 June; total blockade 23 to 24 June; airlift; blockade ended May 1949.
• Consequences. West stayed; Berlin and Europe divided for over 40 years; West Germany created; containment shown to have teeth; NATO 1949; Warsaw Pact 1955, triggered by West Germany joining NATO and rearming in May 1955.
• The boundaries. Taking Eastern Europe to 1948 is yours; holding it from 1948 is Key Question 6. The Blockade is yours; the Wall is Key Question 6. The Truman Doctrine is yours; Korea, Cuba and Vietnam are Key Question 5.
• The question number. Every one of the 25 mark schemes in this corpus that set this Key Question set it at Question 7. The 2027 syllabus has removed a whole key question from Option B, so treat that as a pattern, not a guarantee.

11. Where these facts come from

Taken from Cambridge's own published 0470 materials, meaning the syllabus for 2027 and 2028, the Paper 1 mark schemes for 2018 to 2024, the Paper 2 question papers and mark schemes, and the Principal Examiner reports:

the Key Question, focus points and specified content wording; the Section A structure and the two-from-1-to-3 and two-from-4-to-6 rule; the Paper 2 prescribed topics for 2027 and 2028; every Yalta and Potsdam decision and disagreement listed; the Curzon Line and the Oder-Neisse Line; the Allied Control Council; the Lublin and London Poles; the rigged Polish election of 1947; the whole Czechoslovak sequence including Beneš, Masaryk, Gottwald and the February 1948 coup; Cominform 1947 and Comecon 1949 and Tito's expulsion in 1948; the Iron Curtain speech dated to 1946 and Stalin's Pravda reply of 16 March 1946; the Long Telegram of 22 February 1946 and the Novikov telegram of 27 September 1946; the Truman Doctrine of 12 March 1947; the Greek Civil War sequence including the British withdrawal in February 1947 and the communist defeat in 1949; the Marshall Plan announcement of June 1947 and the text of Marshall's speech; Berlin lying 100 miles inside the Soviet zone; the announcement of a separate West German state on 1 June 1948, the new currency on 18 June, the Soviet response on 23 June and the total blockade on 23 to 24 June; the blockade ending in May 1949; NATO in 1949; the Warsaw Pact in 1955 and West Germany joining NATO and rearming in May 1955; every examiner-flagged error in section 9; and every quoted phrase, each of which is Cambridge's own wording from a mark scheme, an examiner report or a set source.

Where Cambridge's own materials disagree with each other

These are real conflicts inside Cambridge's published documents. Do not try to reconcile them, and do not quote the disputed figure as if it were settled. Give the round version, or leave the number out and explain the mechanism instead. None of these numbers is needed for a top answer.

How many airlift flights, and how much cargo. A 2019 Paper 1 mark scheme prints "27 500 trips to Berlin supplied 2 million tons of supplies." A 2022 Paper 1 mark scheme prints "over 300 000 flights." A 2024 Paper 2 source prints "277 500 flights had delivered 2.3 million tons of food." A separate 2020 mark scheme gives a rate rather than a total: the airlift "reached 8000 tons a day" by April 1949. The safe form in an exam answer is that the airlift ran for months, flew hundreds of thousands of sorties and delivered millions of tons.

When the blockade ended. One 2024 Paper 2 source says "the blockade ended on 12 May 1949." The source printed next to it says "the Soviets backed down on 11 May, although the airlift did not end until September." Cambridge's own part (a) on that paper asks candidates how far the two sources agree, which tells you the exam board knows. Say May 1949.

When Bizonia was formed. A 2023 mark scheme prints "In 1946 the American and British zones were merged into one zone called Bizonia." A 2024 mark scheme prints "In 1947, the USA and Britain formed a united economic unit out of their zones" and adds that the French joined in 1948. Say that the western zones were merged in the years before the blockade.

How much the Marshall Plan cost. A 2024 Paper 2 source states "The Marshall Plan cost the United States $17.6 billion." A 2020 mark scheme credits, as a valid candidate point, "the US gave over $12 billion to Europe." Say billions of dollars.

How many Soviet citizens died in the war. A mark scheme and an examiner report both use 20 million. But Stalin, in the Pravda interview Cambridge sets as a source, says "about 7 million people." These are not the same kind of claim. The first is Cambridge's own figure; the second is a contemporary Soviet public statement, and its lowness is itself a fact about the source, not a correction to the first.

Things left out because this corpus could not verify them

These appear in most textbooks and are probably right, but they do not appear in the 0470 syllabus, mark schemes, examiner reports or set sources read for these notes. Check them against your own textbook before writing them as precise:

• the place and exact date of Churchill's Iron Curtain speech, and the word Fulton, which appears nowhere in this corpus
• the exact dates of the Yalta and Potsdam conferences beyond the months February and July 1945
• the exact date of the atomic test, and the date and place Truman told Stalin
• the full membership list of NATO in 1949 and of the Warsaw Pact in 1955
• the exact number of countries that accepted Marshall Aid
• casualty and cost figures for the airlift, including aircraft lost
• the exact date the Federal Republic of Germany and the German Democratic Republic were founded

None of these is needed for a Level 5 answer, which is why they are absent from the body above rather than asserted.

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