Interwar Period Timeline

The newly formed Russian Soviet Federative Socialist Republic declared war on Poland in 1919. The conflict lasted until 1921 and resulted in a Polish victory.

Image source: Polish–Soviet War

The Soviet Union was formally established in 1922 under the leadership of Vladimir Lenin, consolidating Bolshevik control over the former territories of the Russian Empire after years of civil war.

Image source: Treaty on the Creation of the Union of Soviet Socialist Republics

When Germany defaulted on its reparation payments, French and Belgian troops occupied the heavily industrialised Ruhr district in January 1923, deepening Germany's economic crisis.

Image source: Occupation of the Ruhr

Vladimir Lenin's death in 1924 led to a power struggle between various members of the Communist Party, ultimately shaping the future leadership of the Soviet Union.

Image source: Death and state funeral of Vladimir Lenin

Mounting tension in British India, particularly in the Punjab region, culminated in the Amritsar Massacre in 1919. The Government of India Act 1919 had failed to satisfy demands for self-rule, fueling growing nationalist sentiment.

Image source: Jallianwala Bagh massacre

Abd el-Krim founded an independent Rif Republic, which operated until 1926 but had no international recognition. Spain and France sent 200,000 soldiers, forcing el-Krim to surrender in 1926; he was exiled until 1947. Morocco became a base from which Spanish Nationalists launched their rebellion in 1936.

Image source: Republic of the Rif

Spanish forces, facing unrest in Morocco off and on since the 1890s, were massacred at the Battle of Annual in 1921, a humiliating defeat that emboldened Berber resistance leader Abd el-Krim.

Image source: Battle of Annual

In 1922, the Kingdom of Egypt was granted formal independence by Britain, though it continued to be a client state following British guidance.

The right of the Dominions to set their own foreign policy was recognised in 1923 and formalised by the 1931 Statute of Westminster, granting legislative independence to Canada, Australia, New Zealand, South Africa, and Ireland.

Image source: Statute of Westminster 1931

Mandatory Iraq, a British mandate since 1920, gained official independence as the Kingdom of Iraq in 1932 when King Faisal agreed to British terms of a military alliance and an assured flow of oil.

Image source: Kingdom of Iraq

In Italy, the National Fascist Party came to power under Benito Mussolini after threatening a March on Rome in October 1922. Mussolini was appointed Prime Minister, beginning two decades of Fascist rule in Italy.

Image source: March on Rome

Mussolini resolved the question of sovereignty over the Dodecanese at the 1923 Treaty of Lausanne, which formalised Italian administration of both Libya and the Dodecanese Islands in return for a payment to Turkey, though he failed to extract a mandate over part of Iraq from Britain.

Image source: Treaty of Lausanne

In November 1923, Adolf Hitler attempted an armed coup in Munich known as the Beer Hall Putsch. The failed putsch marked an early episode of Nazi agitation during the Weimar Republic's turmoil.

Image source: Beer Hall Putsch

A confrontation between Britain and Italy led to the resolution of the question of Jubaland in 1924, when the territory was merged into Italian Somaliland as part of Mussolini's colonial ambitions.

Image source: Oltre Giuba

Hitler came to power in January 1933 and inaugurated an aggressive policy designed to give Germany economic and political domination across central Europe. Until August 1939, the Nazis denounced Communists, the Soviet Union, and Jews as their greatest enemies.

Image source: Adolf Hitler's rise to power

Italy invaded and occupied Abyssinia (Ethiopia) in the Horn of Africa in 1935–1936, defying the League of Nations. Italy had also demanded mandates over the former German Cameroon and a free hand in Ethiopia in 1932 and 1935 in exchange for supporting the Stresa Front against Germany.

Image source: Second Italo-Ethiopian War

In July 1936, Francisco Franco of the Nationalist faction requested Italian support against the ruling Republican faction, guaranteeing friendly future relations and greater Roman influence in Spanish politics.

Image source: International response to the Spanish Civil War

Spain, unstable politically for centuries, was wracked from 1936 to 1939 by one of the bloodiest civil wars of the 20th century. Marked by numerous battles, sieges, and atrocities, it ended when the Nationalists won by overwhelming the Republican forces.

Image source: Spanish Civil War

After establishing the Rome-Berlin Axis with Mussolini and signing the Anti-Comintern Pact with Japan, Hitler saw Italy join the pact a year later in 1937, feeling able to take the offensive in foreign policy.

Image source: Anti-Comintern Pact

On 12 March 1938, German troops marched into Austria, considered a German state, where an attempted Nazi coup had been unsuccessful in 1934, completing the annexation of Austria into the Reich.

Image source: Anschluss

At the Munich Conference of September 1938, Hitler, Mussolini, Chamberlain, and Daladier agreed upon the cession of Sudeten territory to the German Reich by Czechoslovakia—a prime example of appeasement.

Image source: Munich Agreement

Barely six months after Munich, Hitler used the quarrel between Slovaks and Czechs as a pretext for taking over the rest of Czechoslovakia as the Protectorate of Bohemia and Moravia in March 1939.

Image source: Protectorate of Bohemia and Moravia

Ahmet Zogu, who had proclaimed himself King of Albania in 1928, failed to create a stable state. In 1939, Italy invaded and annexed Albania as a separate kingdom in personal union with the Italian crown.

Image source: Italian invasion of Albania

The Weimar Republic suffered a first episode of political and economic turmoil culminating in the German hyperinflation of 1923, which wiped out savings and destabilised German society.

Image source: Hyperinflation in the Weimar Republic

Between 1929 and 1932, worldwide GDP fell by an estimated 15%, compared with less than 1% during the Great Recession of 2008–2009, demonstrating the unprecedented severity of the global downturn.

Image source: Great Depression

The Great Depression originated in the United States and became worldwide news with the stock market crash of 29 October 1929, known as Black Tuesday. It was the longest, deepest, and most widespread depression of the 20th century, lasting until the late 1930s.

Image source: Wall Street Crash of 1929

In September 1931, the Japanese Kwantung Army—acting without government approval—seized control of Manchuria from warlord Zhang Xueliang, defying international opinion and escalating tensions in East Asia.

Image source: Japanese invasion of Manchuria

Prime Minister Inukai Tsuyoshi tried to negotiate with China but was assassinated in the May 15 Incident of 1932, ushering in an era of nationalism and militarism led by the Imperial Japanese Army. The IJA's nationalism ended civilian rule in Japan until after 1945.

Image source: May 15 incident

The League of Nations, effectively controlled by Britain and France, issued the Lytton Report in 1932, saying that Japan had genuine grievances but acted illegally in seizing the entire province of Manchuria.

Image source: Lytton Report

Large-scale warfare between China and Japan began in August 1937, with naval and infantry attacks focused on Shanghai that quickly spread to other major Chinese cities.

Image source: Second Sino-Japanese War

Japanese forces committed numerous large-scale atrocities against Chinese civilians, most infamously the Nanjing massacre in December 1937, involving mass murder and mass rape.

Image source: Nanjing Massacre

The Japanese Army fared badly in large border battles with the Soviet Red Army in Mongolia at the Battles of Khalkhin Gol in summer 1939, deterring Japan from further attacks northward.

Image source: Battles of Khalkhin Gol