January 15 - Rosa Luxemburg and Karl Liebknecht, two of the most prominent socialists in Germany, are tortured and murdered by the Freikorps.
January 16 - Temperance movement: The United States ratifies the Eighteenth Amendment to the United States Constitution, authorizing Prohibition in the United States one year after ratification.
January 18 - World War I: The Paris Peace Conference opens in Versailles, France.
January 18 - Ignacy Jan Paderewski becomes Prime Minister of the newly independent Poland.
January 21 - Meeting of the First Dáil Éireann in the Mansion House Dublin, Sinn Féin adopts Ireland's first constitution. The first engagement of Irish War of Independence, Sologhead Beg, County Tipperary.
January 22 - Act Zluky is signed, unifying the Ukrainian People's Republic and the West Ukrainian National Republic.
February 21 - Kurt Eisner, German socialist, is assassinated. His death results in the establishment of the Bavarian Soviet Republic and parliament and government fleeing Munich, Germany.
February 23 - Benito Mussolini forms the Fascist Party in Italy.
February 25 - Oregon places a 1 cent per U.S. gallon tax on gasoline, becoming the first U.S. state to levy a gasoline tax.
February 26 - An act of the U.S. Congress establishes most of the Grand Canyon as a United States National Park (see Grand Canyon National Park).
March 2 - The first Communist International meets in Moscow.
March 23 - In Milan, Italy, Benito Mussolini founds his Fascist political movement.
April 6 - Mohandas Karamchand Gandhi orders a General Strike.
April 10 - Mexican Revolution leader Emiliano Zapata is ambushed and shot dead by government forces in Morelos.
April 11 - The International Labour Organization is founded.
April 13 - The Establishment of the Provisional Government of the Republic of Korea.
April 13 - Jallianwala Bagh massacre: British troops massacre at least 379 unarmed demonstrators in Amritsar, India. At least 1200 wounded.
April 16 - Mohandas Gandhi organizes a day of "prayer and fasting" in response to the British slaughter of Indian protesters in the Amritsar Massacre.
April 19 - Leslie Irvin of the United States makes the first successful voluntary free-fall parachute jump using a new kind of self-contained parachute.
May 4 - May Fourth Movement: Student demonstrations take place in Tiananmen Square in Beijing, China, protesting the Treaty of Versailles, which transferred Chinese territory to Japan.
May 8 - Edward George Honey first proposes the idea of a moment of silence to commemorate The Armistice of World War I, which later results in the creation of Remembrance Day.
May 15 - The Winnipeg General Strike begins. By 11:00 a.m., almost the whole working population of Winnipeg, Manitoba had walked off the job.
May 16 - A naval Curtiss aircraft NC-4 commanded by Albert Cushing Read leaves Trepassey, Newfoundland, for Lisbon via the Azores on the first transatlantic flight.
May 17 - War Department (UK) orders use of National Star Insignia on all airplanes.
May 19 - Mustafa Kemal Atatürk lands at Samsun on the Anatolian Black Sea coast, initiating what was later termed the Turkish War of Independence. The anniversary of this event is the official date of commemoration of the Pontic Greek Genocide in Greece and Cyprus.
May 27 - The NC-4 aircraft arrives in Lisbon after completing the first transatlantic flight.
May 29 - Einstein's theory of general relativity is tested (later confirmed) by Arthur Eddington's observation of a total solar eclipse in Principe and by Andrew Crommelin in Sobral, Ceará, Brazil.
June 4 - Women's rights: The U.S. Congress approves the 19th Amendment to the United States Constitution, which guarantees suffrage to women, and sends it to the U.S. states for ratification.
June 7 - Sette giugno: Riot in Malta; four are killed.
June 11 - Sir Barton wins the Belmont Stakes, becoming the first horse to win the Triple Crown.
June 14 - John Alcock and Arthur Whitten Brown depart St. John's, Newfoundland on the first nonstop transatlantic flight.
June 15 - John Alcock and Arthur Brown complete the first nonstop transatlantic flight at Clifden, County Galway, Ireland.
June 20 - 150 die at the Teatro Yaguez fire, Mayagüez, Puerto Rico.
June 21 - The Royal Canadian Mounted Police fire a volley into a crowd of unemployed war veterans, killing two, during the Winnipeg General Strike.
June 21 - Admiral Ludwig von Reuter scuttles the German fleet in Scapa Flow, Orkney. The nine sailors killed were the last casualties of World War I.
June 23 - Estonian Liberation War: The decisive defeat of German Freikorps forces in the Battle of Cesis. This day is celebrated as Victory Day in Estonia.
June 28 - The Treaty of Versailles is signed in Paris, formally ending World War I between Belgium, Britain, France, Italy, the United States and allies on the one side and Germany and Austria Hungary on the other side.
July 6 - The British dirigible R34 lands in New York, completing the first crossing of the Atlantic Ocean by an airship.
July 11 - The eight-hour working day and free Sunday become law in the Netherlands.
July 13 - The British airship R34 lands in Norfolk, England, completing the first airship return journey across the Atlantic in 182 hours of flight.
July 19 - Following Peace Day celebrations marking the end of World War I, ex-servicemen rioted and burnt down Luton Town Hall.
July 21 - The dirigible Wingfoot Air Express crashes into the Illinois Trust and Savings Building in Chicago, killing 12 people.
July 31 - German national assembly adopts the Weimar constitution (which comes into force on August 14)
August 11 - Constitution of Weimar Republic adopted.
August 19 - Afghanistan gains full independence from the United Kingdom.
September 4 - Mustafa Kemal Atatürk, who founded the Republic of Turkey, gathers a congress in Sivas to make decisions as to the future of Anatolia and Thrace.
September 10 - Austria and the Allies sign the Treaty of Saint-Germain recognizing the independence of Poland, Hungary, Czechoslovakia and Yugoslavia.
September 16 - The American Legion is incorporated.
September 17 - Massacre of Turkic peoples in the village of Hakmehmet, in Igdir Province, Turkey, by Armenians.
September 18 - The Netherlands gives women the right to vote.
September 18 - Fritz Pollard becomes the first African-American to play professional football for a major team, the Akron Pros.
September 22 - The steel strike of 1919, led by the Amalgamated Association of Iron and Steel Workers, begins in Pennsylvania before spreading across the United States.
October 2 - US President Woodrow Wilson suffers a massive stroke, leaving him partially paralyzed.
October 7 - KLM of the Netherlands was founded. It is the oldest airline still operating under its original name.
October 9 - Black Sox scandal: The Cincinnati Reds "win" the World Series.
October 10 - Richard Strauss' opera Die Frau ohne Schatten receives its debut performance in Vienna.
October 28 - The U.S. Congress passes the Volstead Act over President Woodrow Wilson's veto, paving the way for Prohibition to begin the following January.
November 10 - The first national convention of the American Legion is held in Minneapolis, Minnesota, ending on November 12.
November 11 - The Centralia Massacre in Centralia, Washington results the deaths of four members of the American Legion and the lynching of a local leader of the IWW.
November 27 - Haiti becomes a signatory to the Buenos Aires copyright treaty.
November 28 - Lady Astor is elected as a Member of the Parliament of the United Kingdom. She is the first woman to sit as a British MP, although not the first to be elected
December 1 - Lady Astor becomes first female member of the British Parliament to take her seat (she had been elected to that position on November 28).
December 17 - Uruguay becomes a signatory to the Buenos Aires copyright treaty.
December 26 - Babe Ruth of the Boston Red Sox is sold to the New York Yankees by owner Harry Frazee.
December 30 - Lincoln's Inn in London admits its first female bar student.
