• Germany invaded Poland on 3rd September 1939, starting WWII — just 21 years after WWI ended.
• Three historical viewpoints exist: the orthodox view (Hitler planned it all), the revisionist view (Hitler was an opportunist exploiting a weak system), and a middle view (both are partly true).
• The Treaty of Versailles humiliated Germany and created the resentment that helped Hitler rise to power.
• The League of Nations failed repeatedly (Manchuria 1931, Abyssinia 1935) — proving to Hitler it wouldn't stop him.
• Hitler broke the Treaty of Versailles step by step: rearmament (1933) → Rhineland (1936) → Anschluss (1938) → Sudetenland (1938) → rest of Czechoslovakia (1939).
• Appeasement — Britain and France's policy of giving in to avoid war — let Hitler get away with each of these moves.
• The Nazi-Soviet Pact (August 1939) removed Hitler's fear of a two-front war and cleared the way for the invasion of Poland.
• Britain and France finally abandoned appeasement, guaranteed Poland's borders, and declared war when Hitler invaded.

Let's set the scene. The Second World War began on 3rd September 1939 — but you can't understand *why* it started without understanding the alliances and the years of build-up that came before it.

Who Was On Whose Side?

Here's a twist that catches a lot of students out: the USSR actually started the war on Germany's side — sort of. They'd signed a non-aggression pact with Germany in August 1939 (the Nazi-Soviet Pact). It was only when Germany broke that pact and invaded Russia in 1941 that the USSR flipped to join the Allies.

Three Historical Viewpoints — This Is the Heart of the Debate

Every exam question on this topic is really asking you to weigh up these three interpretations. Get comfortable with all three, because you'll need to use them to argue both sides.

Causes & Consequences of Hitler's Foreign Policy — The Big Picture

Europe's Reaction to the Treaty (1919)

Think of the Treaty of Versailles reaction as four very different moods in one room:

But here's the key thing to remember: by 1923, British opinion had flipped. The public began to think the treaty was too harsh on Germany, and Britain started fearing the USSR (communism) more than Germany — so they actually wanted a strong Germany to act as a buffer against communism. This shift in mood is a big reason appeasement later felt reasonable to so many British people.

The "Stab in the Back" — Dolchstoss

Many Germans believed their own politicians had betrayed them by signing the Treaty of Versailles. This belief was called the dolchstoss ("stab in the back"), and the politicians who signed it were branded the "November Criminals" — named after the month the armistice was signed. This resentment festered for years and became fuel for extremist parties like the Nazis.

Hitler's Rise & Mein Kampf

The Treaty devastated Germany economically — reparations caused two economic depressions in a decade. As the government kept following the treaty's terms, public resentment grew, and extremist parties (like the KPD and NSDAP) gained support. After his failed Munich Putsch, Hitler was jailed — and it was in prison that he wrote Mein Kampf ("My Struggle"), which laid out his core beliefs:

Manchuria (1931) and Abyssinia (1935)

Before Hitler even started breaking rules, the League of Nations had already shown it was a paper tiger. In 1931, Japan invaded Manchuria; in 1935, Italy invaded Abyssinia. Both crises taught Hitler an extremely important lesson.

Think of it like a teacher who keeps threatening detention but never actually gives one — eventually, no student takes the threat seriously. That's exactly the position the League was in by 1935.

Germany Leaves the League (November 1933)

Germany's exit from the League freed Hitler to pursue an aggressive foreign policy without needing to justify himself to anyone. His rearmament programme began almost immediately — and many British people actually believed Germany was right to rearm, both because the Treaty had been too harsh, and because other countries were rearming too.

Hitler even used mass rallies — like the 1935 "Rally of Freedom" at Nuremberg, where compulsory military service was reintroduced — to openly flaunt Germany's growing military strength and thumb his nose at the Treaty's restrictions.

The Saar Plebiscite (1935)

The Saar was a coal-rich region on the French-German border, controlled by the League of Nations for 15 years under the Treaty of Versailles. Both France and Germany wanted it.

Was this a success for the League? Sort of — legally, they stuck to the 15-year time limit and avoided war between France and Germany. But it was also a huge propaganda victory for Hitler, proving his popularity even in a region with Nazi opponents — and it gave him valuable natural resources for his rearmament industries.

Remilitarisation of the Rhineland (1936)

This is one of the most important events in the whole chapter — historians often call it "the League's last chance to stop Hitler without a full-scale war."

The Rhineland, an area of western Germany bordering France, had been demilitarised under Versailles — and Germany had even accepted this again in the 1925 Locarno Treaty. Hitler used the Franco-Soviet Treaty of Mutual Assistance (1935) as an excuse, claiming Germany was "surrounded by enemies," and marched troops in.

The result? Hitler built the Siegfried Line (a system of fortifications) along the French border and, crucially, gained massive confidence. He'd got away with a direct, undeniable breach of Versailles — and this taught him that manipulation worked. Right after the invasion, he cleverly signed a 25-year non-aggression pact with France and Britain, with absolutely no intention of keeping it — just to look less threatening.

The Spanish Civil War (1936–1939)

Civil war broke out in Spain between the left-wing government and General Franco's right-wing nationalist rebels.

On 26th April 1937, German and Italian bombers destroyed the city of Guernica, killing hundreds of civilians in just three hours — this shocked world leaders and pushed Britain and France to increase their own rearmament. This war was hugely important for Hitler: Germany tested the concept of blitzkrieg ("lightning war"), developed new bombing techniques, and cemented the Rome-Berlin Axis alliance with Mussolini (1937).

What Was Appeasement?

Appeasement was the policy of giving in to demands to avoid war — using diplomacy and treaties to accommodate aggressive nations rather than confronting them. Britain and France followed this policy throughout the 1930s, and it's most closely associated with British PM Neville Chamberlain (PM from 1937).

Chamberlain, like many politicians of his generation, had personally lost family in WWI (his brother was killed in 1915) — the horror of that war made him determined to do anything to avoid another one. Not everyone agreed though: Winston Churchill was appeasement's fiercest critic, famously saying:

"An appeaser is one who feeds a crocodile, hoping it will eat him last."

Arguments For and Against Appeasement

The Anglo-German Naval Agreement (1935)

In April 1935, Britain, France, and Italy formed the Stresa Front, agreeing to oppose Hitler's foreign policy and challenge any breaches of Versailles. By June, it had already collapsed — the Abyssinian Crisis had ruined Italy's relationship with Britain and France, and Britain unilaterally signed the Anglo-German Naval Agreement with Germany.

Anschluss (1938)

Around 98% of Austrians spoke German, and many felt Austria had a weak economy without union with Germany — plus there was a strong Nazi Party inside Austria itself. Here's how Hitler engineered the union:

Was Anschluss a success for appeasement? It arguably reversed a harsh, unpopular part of Versailles peacefully. But Hitler gained 100,000 soldiers and vital raw materials (steel, iron) — and Germany now surrounded Czechoslovakia on three sides, setting up his next target.

The Sudeten Crisis & the Munich Conference (1938)

Why did Hitler want the Sudetenland? Multiple overlapping reasons:

• It would help "protect" Germany, since Czechoslovakia now bordered Germany on three sides after Anschluss
• Rich mineral resources plus the Skoda armament factory would boost German industry
• The Sudetenland's fortifications made the rest of Czechoslovakia much easier to invade later
• Over 3.5 million Germans lived there and claimed Czech mistreatment — fitting Hitler's Grossdeutschland and Lebensraum aims perfectly

Success or failure? It gave Britain more time to rearm, and technically many Germans lived there — but it also handed Hitler the Sudetenland's valuable defences, leaving the rest of Czechoslovakia completely vulnerable to invasion.

Invasion of Czechoslovakia (March 1939) — Appeasement's Breaking Point

By March 1939, Hitler seized the rest of Czechoslovakia — threatening to bomb Prague if the government didn't surrender, marching in on 15th March, and encouraging Slovakia to declare independence. Crucially, this time there was no German-speaking population to justify the invasion — Hitler simply wanted more power. This was the moment appeasement finally died. Chamberlain stated on 17th March that he could no longer trust Hitler, and Britain and France began actively looking to protect other vulnerable countries.

This is a genuinely shocking event in the story — two ideological arch-enemies suddenly shaking hands. Understanding why both sides did it is essential.

Why Were Hitler and Stalin Enemies?

• Opposite ideologies: Hitler was Fascist (far-right); Stalin was Communist (far-left)
• Opposing aims for Europe: Hitler wanted German domination; Stalin wanted to spread communism
• They'd fought on opposite sides of the Spanish Civil War

Yet on 23rd August 1939, they signed the Nazi-Soviet Pact (also known as the Molotov-Ribbentrop Pact) — a move that genuinely shocked the world.

The public part of the pact shocked Britain and France — but it was the secret partitioning of Poland that mattered most. Germany invaded Poland just nine days after signing.

Other Alliances That Backed This Up

Stalin was also increasingly worried about the power of Fascism and an old enemy — Japan (who had beaten Russia in 1904 and controlled neighbouring Manchuria). The Nazi-Soviet Pact gave him temporary protection from both Japan and Germany. But the pact was always doomed — the Anti-Comintern Pact made clear Hitler didn't actually support communism, and in 1941 he broke the pact entirely by invading Russia in Operation Barbarossa.

The British-French Guarantee of Poland (March 1939)

After Hitler took Czechoslovakia, Britain and France realised his aggressive policy wasn't stopping — his next likely target was clearly Poland. Why?

• The Polish Corridor cut Germany's territory into two
• The free city of Danzig (once German, still full of Germans) sat inside Poland — and Hitler had already demanded its return
• Hitler was clearly expanding eastwards, and Czechoslovakia bordered Poland directly

Crucially, by March 1939, Britain and France had officially abandoned appeasement — they no longer believed Hitler would stop, and had made real progress rearming. On 31st March 1939, they made a formal agreement to protect Poland's borders.

The Final Countdown to War

"This morning the British ambassador in Berlin handed the German government a final note stating that unless we heard from them by 11 o'clock that they were prepared at once to withdraw their troops from Poland, a state of war would exist between us... consequently this country is at war with Germany." — Chamberlain's radio broadcast, 3rd September 1939

Key Terms

Essential Dates

• I can explain the orthodox vs revisionist interpretations of WWII's causes
• I understand how the Treaty of Versailles created long-term German resentment
• I can explain the dolchstoss and "November Criminals"
• I know Hitler's key foreign policy aims from Mein Kampf (Aryan superiority, Lebensraum, revising Versailles, Grossdeutschland)
• I can explain why the Manchurian and Abyssinian Crises encouraged Hitler
• I understand why the remilitarisation of the Rhineland was the League's "last chance" to stop Hitler
• I can explain the significance of the Spanish Civil War for Nazi Germany's military development
• I understand the arguments for and against appeasement (Chamberlain vs Churchill)
• I can describe how Anschluss was achieved, step by step
• I can explain the causes and outcomes of the Sudeten Crisis and Munich Conference
• I understand why the invasion of the rest of Czechoslovakia ended appeasement
• I can explain why BOTH Hitler and Stalin agreed to the Nazi-Soviet Pact
• I know the secret terms of the pact regarding Poland's partition
• I can explain the events leading from the invasion of Poland to Britain's declaration of war
• I can weigh up all five causes of WWII in a balanced essay conclusion