International relations (1918–1939)

International relations (1918–1939)
Period	1918–1939
Major events	Paris Peace Conference (1919–1920), Treaty of Versailles (1919), League of Nations, Great Depression
Major powers	United Kingdom, France, United States, Japan, Italy, Germany, Soviet Union
Ideologies	Liberalism (international relations), Communism, Fascism, Nazism
Outcome	Prelude to World War II

International relations (1918–1939) The interwar period between 1918 and 1939 saw the collapse of empires such as the Austro-Hungarian Empire, Ottoman Empire, and Russian Empire and the rise of new states like Czechoslovakia, Yugoslavia, and Poland (Second Republic), while diplomacy oscillated between efforts at collective security through the League of Nations and aggressive revisionism by Nazi Germany, Fascist Italy, and expansionist Imperial Japan. Key conferences, treaties, crises, and economic turmoil reshaped alliances and ideological alignments, setting the stage for the outbreak of the Second World War.

Background and aftermath of World War I

The armistice that ended fighting on the Western Front involved actors such as the German Empire, Allied Powers, and delegations from the Weimar Republic, and was followed by political upheavals including the German Revolution of 1918–1919, the Russian Civil War, and interventions by the Entente powers in the Baltic states and Poland (Second Republic). The Paris Peace Conference (1919–1920) produced the Treaty of Versailles (1919), the Treaty of Saint-Germain-en-Laye (1919), and the Treaty of Trianon (1920), which redrew borders affecting Austria, Hungary, and Romania while sparking disputes over minorities in Silesia and Alsace-Lorraine. Revolutionary movements inspired by the Bolshevik Revolution and personalities such as Vladimir Lenin, Leon Trotsky, and later Joseph Stalin influenced both domestic policy and transnational communist networks like the Comintern.

Peace settlements and the League of Nations

The creation of the League of Nations at the Paris Peace Conference (1919–1920) aimed to manage disputes among states including Belgium, Italy, and Japan, and to administer mandates in former Ottoman Empire provinces such as Iraq and Syria (Mandate). Key legal instruments like the Minorities Treaty system and commissions at Geneva sought to stabilize borders involving Greece, Bulgaria, and Turkey (Republic) after the Greco-Turkish War (1919–1922). The absence of United States ratification of the Treaty of Versailles (1919) and non-membership of powers like Germany until 1926 weakened the League of Nations’s capacity to enforce decisions during crises such as the Manchurian Crisis and the Italian invasion of Ethiopia.

Major powers and diplomacy (United Kingdom, France, United States, Japan)

The United Kingdom pursued policies balancing imperial maintenance in India, Egypt, and Iraq with naval treaties like the Washington Naval Treaty (1922–1923) and engagements at conferences including Washington Naval Conference. France prioritized security against Germany through alliances with Poland (Second Republic), the Little Entente, and fortifications exemplified by the Maginot Line, while figures such as Raymond Poincaré and Aristide Briand shaped Franco-German diplomacy. The United States under presidents Woodrow Wilson, Warren G. Harding, and Franklin D. Roosevelt oscillated between idealism embodied in the Fourteen Points and isolationism visible in tariff policies like the Smoot–Hawley Tariff Act (1930). Imperial Japan expanded influence through episodes including the Twenty-One Demands, the Mukden Incident, and participation in the League of Nations until withdrawal after the Lytton Report.

Revisionist powers and rising totalitarian states (Germany, Italy, Soviet Union)

Germany (Weimar Republic)’s humiliation under the Treaty of Versailles (1919), hyperinflation of 1923, and political crises paved the way for the rise of the National Socialist German Workers' Party and leaders like Adolf Hitler, who pursued rearmament and territorial revisionism culminating in the Remilitarization of the Rhineland (1936). Italy under Benito Mussolini sought imperial expansion in Ethiopia and intervention in the Spanish Civil War (1936–1939), while championing Fascism as an ideology. The Soviet Union under Joseph Stalin consolidated power via Five-year Plans and purges, signed treaties such as the Treaty of Rapallo (1922) and later the Molotov–Ribbentrop Pact (1939), and engaged in the Soviet western border conflicts and support for republican forces in Spain.

Regional conflicts and crises (Eastern Europe, Balkans, Middle East, Asia)

Eastern Europe witnessed disputes over Vilnius, Memel, and Upper Silesia involving Lithuania, Latvia, Poland (Second Republic), and Czechoslovakia, alongside tensions in the Balkans among Yugoslavia, Greece, and Bulgaria. The Middle East saw mandates and uprisings in Palestine (Mandate), the Arab Revolt, and state formation in Iraq and Transjordan. In Asia, China (Republic) endured the Warlord Era, the Northern Expedition of the Kuomintang, clashes with Imperial Japan in Manchuria and at Shanghai (1937), and internal conflicts between the Chinese Communist Party and the Kuomintang.

Economic factors and the Great Depression

Global economic integration after the First World War—through reparations, loans involving the Dawes Plan (1924) and the Young Plan (1929), and trade ties—collapsed with the Wall Street Crash of 1929 and the Great Depression, provoking protectionism like the Smoot–Hawley Tariff Act (1930) and financial crises in Germany (Weimar Republic), Austria, and Hungary. Economic distress fueled support for radical movements including National Socialism, Fascism, and Communism, shifted voting patterns in France and the United Kingdom, and constrained rearmament and diplomatic flexibility.

Arms control, disarmament efforts, and appeasement maneuvers

International initiatives such as the Washington Naval Conference, the Kellogg–Briand Pact (1928), and the Geneva Disarmament Conference (1932–1934) sought to limit armaments among United States, United Kingdom, France, and Japan but produced limited enforcement. The policy of appeasement, enacted by leaders like Neville Chamberlain and supported by segments in British and French politics, culminated in agreements such as the Anglo-German Naval Agreement (1935) and the Munich Agreement (1938), while military responses to aggression—such as sanctions against Italy after Ethiopia—proved ineffective. These failures, combined with clandestine pacts like the Anti-Comintern Pact and eventual bilateral accords, realigned power blocs and removed restraints on expansionist regimes, precipitating the collapse of the interwar settlement and the onset of global war.

Category:Interwar period