Europe During the Interwar Period

By the end of this lesson, students will be able to:

• Account for how various political and ideological factors produced the catastrophe of the Second World War (Skill 5.B; LO J).
• Account for KC-4.1.III: how interwar fascism, extreme nationalism, racist ideologies, and the failure of appeasement combined to produce the Second World War.
• Account for KC-4.1.III.A: how French and British fears of another war, American isolationism, and Western distrust of the Soviet Union allowed the fascist states to rearm and expand their territory.
• Connect the chain of interwar fascist territorial advances from Ethiopia in 1935 through the invasion of Poland in 1939 (Skill 5.B in direct practice).
• Explain the political logic of appeasement, the Munich Agreement, and the Molotov-Ribbentrop Pact as instruments by which Western states sought, and ultimately failed, to contain fascist expansion short of war.

Topic 8.7 covers the political and ideological factors of the 1919-1939 interwar period that produced the Second World War. KC-4.1.III captures the central frame: in the interwar period, fascism, extreme nationalism, racist ideologies, and the failure of appeasement produced the catastrophe of the Second World War. The lesson covers two intersecting stories: the structural fragility of the post-1919 international order, and the chain of fascist territorial advances between 1935 and 1939 that the structural fragility allowed.

The structural fragility of the post-1919 order (KC-4.1.III). The Versailles settlement of 1919 (covered in Topic 8.4) produced a peace framework whose principal guarantors were unable, unwilling, or absent. The United States Senate rejected ratification of the Treaty of Versailles on 19 March 1920 by a vote of 49-35 (short of the two-thirds majority required), defeating Woodrow Wilson's effort to bring the United States into the League of Nations. The American withdrawal from the European order had three principal effects: the League of Nations opened in January 1920 without its principal architect; the United States and Germany signed a separate peace (the Treaty of Berlin) on 25 August 1921; and the broader pattern of American isolationism that the Senate vote symbolized continued through the 1920s and 1930s, including American non-membership in the World Court and the high tariff wall of the 1922 Fordney-McCumber Tariff and the 1930 Smoot-Hawley Tariff.

The Soviet Union sat outside the post-1919 order on different grounds. Bolshevik Russia (covered in Topic 8.3) was excluded from the Paris Peace Conference; Western expeditionary forces had intervened on the White side during the Russian Civil War; the Treaty of Brest-Litovsk in March 1918 had taken Russia out of the war on terms that the Allied powers refused to recognize; and Bolshevik calls for international communist revolution through the Comintern from March 1919 onward produced sustained Western suspicion. The Soviet Union joined the League of Nations only in September 1934 and was expelled in December 1939 after the invasion of Finland. Western distrust of the Soviet Union, and Soviet distrust of the Western democracies, ran in both directions throughout the interwar period and produced the unstable diplomatic geometry that fascist powers exploited.

France and Britain — the two principal Western European powers committed to the post-1919 settlement — were both weakened by the war and by their interwar political and economic difficulties. France had suffered approximately 1.4 million combat deaths in the war (the highest per-capita loss among the major belligerents); the war had been fought largely on French territory; the postwar reconstruction of the devastated departments of the north and east absorbed substantial public spending; and the political instability of the Third Republic (43 governments between 1918 and 1940) produced inconsistent foreign policy. The British political class was divided between a continuing imperial commitment that stretched military resources thin and a political-cultural reaction against the human cost of the 1914-1918 war that produced sustained pacifist sentiment, the 1933 Oxford Union "King and Country" debate, and the 1935 Peace Ballot in which approximately 11 million Britons indicated support for League-based collective security but only roughly 6.8 million indicated support for military action even in defense of League members.

The Western response to fascist rearmament and expansion (KC-4.1.III.A). French and British fears of another war, American isolationism, and deep distrust between the Western democratic capitalist nations and the authoritarian communist Soviet Union allowed the fascist states to rearm and expand their territory. The chain of fascist advances proceeded through eight discrete crises between 1933 and 1939, each one of which presented the Western democracies with a choice between confrontation and accommodation, and in each one of which the Western democracies chose accommodation.

The first crisis was the 1933 German withdrawal from the World Disarmament Conference and from the League of Nations on 14 October 1933, less than nine months after Adolf Hitler's appointment as Chancellor on 30 January 1933. The Geneva Disarmament Conference (1932-1934) had been intended to produce a balanced reduction of European armaments; the German withdrawal effectively ended it. The Western response was a diplomatic protest without consequences. The second crisis was Hitler's announcement of conscription on 16 March 1935, openly violating the Versailles military restrictions. France, Britain, and Italy formally protested at the Stresa Conference of 11-14 April 1935 (the "Stresa Front"); the Anglo-German Naval Agreement of 18 June 1935 then undermined the Stresa Front by accepting German naval rearmament up to 35 percent of the British surface fleet, in direct contradiction of the Versailles naval restrictions.

The third crisis was Italy's invasion of Ethiopia, beginning on 3 October 1935. The League of Nations declared Italy an aggressor and imposed economic sanctions on 18 November 1935 that excluded oil, coal, iron, and steel; the Hoare-Laval Pact of December 1935 (a Franco-British proposal to partition Ethiopia in Italy's favor) was leaked to the French press and abandoned in the resulting public outcry; the Italian conquest of Addis Ababa on 5 May 1936 produced the formal annexation of Ethiopia on 9 May 1936 and the dissolution of the Stresa Front. The League of Nations had failed its first major test of collective security against an aggressor great power.

The fourth crisis was Hitler's remilitarization of the Rhineland on 7 March 1936, openly violating both the Versailles and the Locarno treaties. The German army at this point had only roughly 22,000 troops in the demilitarized zone; the French army was substantially larger and better equipped, and Hitler later admitted that a French move into the Rhineland would have produced a German withdrawal. France did not move; Britain did not press France to move; the Rhineland remained German. The fifth crisis was the Spanish Civil War of 17 July 1936 to 1 April 1939, in which Italy and Germany supported General Francisco Franco's Nationalist forces with roughly 75,000 Italian troops, the German Condor Legion (whose Junkers Ju 87 and Heinkel He 111 aircraft conducted the bombing of Guernica on 26 April 1937), and substantial military equipment. France and Britain organized a Non-Intervention Committee that the Axis powers ignored, while the Soviet Union supported the Republic with limited material and the International Brigades. Franco's victory in 1939 produced a third European fascist state.

The sixth crisis was the Anschluss with Austria on 12-13 March 1938. German troops crossed the Austrian border on the morning of 12 March 1938; Hitler entered Vienna on 14 March; the formal annexation followed a 10 April 1938 plebiscite that returned a 99.7 percent vote in favor. The Western response was a formal protest. The seventh crisis was the Sudeten crisis of summer 1938 and the Munich Agreement of 30 September 1938. The Sudeten German Party of Konrad Henlein had agitated for autonomy from Czechoslovakia since 1933; Hitler used the agitation to demand the cession of the Sudetenland. The Munich Agreement, negotiated by Hitler, Mussolini, Neville Chamberlain, and Edouard Daladier without Czechoslovak representation, transferred the Sudetenland to Germany on terms that Czechoslovakia accepted under Anglo-French pressure. Chamberlain returned to London claiming to have secured "peace for our time"; the policy of appeasement reached its high-water mark.

The Munich Agreement did not stop Hitler. On 15 March 1939 Germany occupied the rest of Czechoslovakia, dissolving the Czechoslovak state in violation of the Munich terms; the Czech lands became the Protectorate of Bohemia and Moravia, and Slovakia became a German client state under Jozef Tiso. The seventh crisis collapsed into the eighth: a British and French guarantee of Polish territorial integrity on 31 March 1939; an Italian invasion of Albania on 7 April 1939; the German-Italian Pact of Steel on 22 May 1939; an Anglo-French diplomatic mission to Moscow in summer 1939 that produced no agreement; and the Molotov-Ribbentrop Pact of 23 August 1939, in which Germany and the Soviet Union pledged mutual non-aggression and (in a secret protocol) divided eastern Europe into German and Soviet spheres of influence. Germany invaded Poland on 1 September 1939; Britain and France declared war on Germany on 3 September 1939; the European war that the Versailles settlement had been intended to prevent had arrived.

The Skill 5.B argument. Topic 8.7's suggested skill is 5.B (Making Connections: account for the way one historical development or process is tied to another). The skill applies in two principal ways. First, students should connect the chain of fascist territorial advances between 1935 and 1939 as a single linked process rather than as eight unrelated events. Each Western accommodation lowered the perceived cost of the next fascist advance and raised the eventual cost of confrontation. Second, students should connect the political-ideological development of fascism (covered in Topic 8.6) and the structural-economic instability of the interwar economy (covered in Topic 8.5) to the geopolitical outcome that Topic 8.7 addresses: the catastrophe of the Second World War that Topic 8.8 will examine in its military phase.

Three sources framing the interwar diplomatic chain: an early statement of postwar reconciliation, the high-water mark of appeasement, and the diplomatic reversal that opened the road to war.

1. (Causation, Skill 5.B) Connect the structural fragility of the post-1919 international order — American absence, Soviet exclusion, and Anglo-French weakness — to the geopolitical opening that fascist states exploited between 1935 and 1939. Cite specific institutional and political factors.
2. (Causation) Account for KC-4.1.III.A: how did French and British fears of another war, American isolationism, and Western distrust of the Soviet Union allow the fascist states to rearm and expand? Cite the German withdrawal from the League in 1933, the Anglo-German Naval Agreement of 1935, and the Hoare-Laval Pact of December 1935.
3. (Causation, Skill 5.B) Connect the chain of fascist territorial advances from the Italian invasion of Ethiopia (October 1935) through the German invasion of Poland (September 1939) as a single linked process rather than as eight unrelated events. What is the principal feature that links them?
4. (Causation) Account for the political logic of the Munich Agreement on 30 September 1938 from the British and French perspectives. Why was appeasement defensible at the time, and why did it fail?
5. (Causation, Skill 5.B) Connect the Anglo-French diplomatic mission to Moscow in summer 1939 and the Molotov-Ribbentrop Pact of 23 August 1939. What does the failure of the Anglo-French-Soviet negotiations reveal about the structural geometry that KC-4.1.III.A identifies?

Draft alignment — pending educator review. AP European History codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, V.1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.