Chronology of Major European Events, 1917-1941

March,
   Nov. 1917
Russian Revolution:  In March the regime of the Tsars falls, and in November Lenin and the Bolsheviks (later Communists) come to power. Russia is effectively out of World War I from this point on, withdrawing formally by the Peace of Brest-Litovsk in March 1918. Civil War wracks the country from 1918 to 1921.
Nov. 1918 End of World War I:  An armistice ends the war with the armies of the Central Powers -- Germany, Austria-Hungary, Bulgaria and Turkey -- all in a state of dissolution. Revolution in Germany overthrows the Kaiser and results in a republic, the so-called Weimar Republic. Austria-Hungary dissolves into its constituent parts.
June 1919 Versailles Treaty:  The Treaty of Versailles is imposed on defeated Germany by Britain, France, and the United States. Germany is forced to cede territory to France (Alsace-Lorraine), Poland (the Polish Corridor, Upper Silesia), Denmark, and Belgium, and forbidden to unite with Austria. Germany also must limit its army to 100,000 men; keep troops out of its Western territories (the "demilitarized" Rhineland); and make heavy reparations payments for damage caused in the war.
Jan. 1920 League of Nations:  The world's first international security organization goes into operation.  The United States does not join, and Germany and Soviet Russia are not admitted.
Fall 1920 Communist International:  The Comintern, founded in obscurity in March 1919, gains the leverage to split the European Socialist parties and establish a more or less significant Communist party in each country. Gradually they are assimilated to the Bolshevik party model, and by the later 1920s nearly all are slavishly subservient to direction from Moscow.
Oct. 1922 Fascism in Italy:  Mussolini becomes Prime Minister of Italy. His regime eventually set up a model that others aspire to imitate, particularly in Eastern Europe and the Balkans. He is not effectively in control until several years later, and is not a major factor in diplomacy until after 1929.
1924-1929 Hopeful years:  An era of good feeling in European international relations witnesses major agreements that ease reparations (the Dawes Plan, 1924 and the Young Plan, 1929) and guarantee frontiers (the Locarno Treaties, 1925).  Germany is admitted to the League of Nations (1926).
Oct. 1926 Stalin in power in Russia:  Stalin defeats the last of his major rivals for power in the period after Lenin's death (Jan. 1924). Over time Stalin's ascendancy brings forced industrialization, brutal police repression and purges, a deeply suspicious attitude toward the outside world, and rigid control over foreign Communist parties.
Oct. 1929 Depression:  The American stock market crash starts a world-wide Depression, which is at its worst in most of Europe from the summer of 1931 through the end of 1932 and in some places much longer.
Sept. 1931 Japan invades Manchuria:  Japanese armies open a long undeclared war against China in Manchuria.  Attempts to restrain Japan through the League of Nations or by other means all fail, weakening faith in the international order.
Jan. 1933 Third Reich:  Hitler becomes Chancellor of Germany. He and his Nazi party are in full command in a matter of months.
Oct. 1933 Germany starts to go it alone:  The Third Reich withdraws from the disarmament conference and the League of Nations.
Jan. 1934 German-Polish Non-Aggression Pact:  This agreement, Hitler's first significant initiative in Eastern Europe, weakens the French policy of security alliances against Germany.
Sept. 1934 Russia joins the League:  Soviet Russia finally joins the League of Nations out of concern about the threat from Nazi Germany.
Mar. 1935 German rearmament:  The Third Reich repudiates the disarmament clauses of the Treaty of Versailles and begins to rearm openly.
Sept. 1935 -
   May 1936
Mussolini's Abyssinian War:  During the international crisis over Italy's invasion of Abyssinia (Ethiopia), all attempts by the League and other forums to agree on effective action to restrain Italy fail. "Collective security" under the League loses much of its remaining credibility. Hitler's support of Mussolini's war brings Germany and Italy into alliance.
Mar. 1936 Reoccupation of the Rhineland:  Nazi Germany repudiates the demilitarization clauses of the Treaty of Versailles and the Locarno Treaties and sends troops into her western territories (the Rhineland).
July 1936 Spanish Civil War:  A civil war breaks out in Spain, lasting until 1939. Germany and Italy support the insurgent Nationalist side (Franco) and send arms and "volunteers"; Britain, France, and Russia support the Republican government but only Russia provides any practical assistance.
Nov. 1936 Formation of the Axis:  The Anti-Comintern Pact loosely connects Germany to Japan and Italy.
Mar. 1938 Anschluss:  Germany annexes Austria after a sudden crisis.
Sept. 1938 Munich Agreement:  A crisis over a large border region in western Czechoslovakia (the so-called "Sudetenland") ends in the Munich agreement between Germany, Britain, France, and Italy, which authorizes German annexation of these territories.
Mar. 1939 Occupation of Prague:  Germany suddenly occupies the rest of western Czechoslovakia and turns Slovakia into a separate client state. This brings the final disillusionment to most British and French "appeasers" who had hoped for a stable settlement with Germany.
Sept. 1939 Start of World War II:  Germany's invasion of Poland is followed by British and French declarations of war on Germany. The Soviet Union, having signed the Nazi-Soviet Pact with Germany a week earlier, remains out of the war and in fact uses the terms of the Pact to justify its occupation of part of Poland, the Baltic States, and parts of Romania over the next year.
Apr. - June
   1940
German victory in the West:  German armies occupy Denmark and Norway starting April 9, the Netherlands, Belgium and Luxembourg starting May 10, and France starting a week later. Thoroughly defeated, France establishes a new government (the "Vichy" government) that is prepared to do Germany's bidding, and signs an armistice.
Apr. 1941 German conquest of the Balkans:  German armies conquer Yugoslavia and Greece in a few weeks.
June 1941 German invasion of Russia:  German armies sweep into the Soviet Union, gaining control of vast territories but failing to knock Russia out of the war. When the United States joins the war in December, Germany is in a war it cannot win, though this does not become apparent to all for another twelve to eighteen months.