- Hatch Act of 1939 enacted.
- Frank Capra releases Mr. Smith Goes to Washington.
- Kenji Mizoguchi releases Story of the Last Chrysanthemum.
- France holds its last public executions.
- Italy declares sovereignty over Albania.
- Eugenio Pacelli becomes Pope Pius XII. His brother Francesco pacelli was the Vatican negotiator for the 1929 Concordat and Laterans Pacts.
- British White Paper advocates policy of limiting Jewish immigration into Palestine to 15,000 per year for 5 years and no further immigration after that point.
- Paperback books are introduced; they sell for 25 cents.
- January 5: Voder (Voice Operated Demonstrator) is first demonstrated at the Franklin Institute in Philadelphia, Pennsylvania.
- January 12: IRA sends manifesto to the British government.
- January 16: IRA bombing campaign in Britain begins with 7 explosions in London, Birmingham and Manchester.
- February 4-6: IRA bombs explode in Britain; 2 civilians hurt in an explosion in the London Underground.
- February 6: Mike Farrell is born.
- March 2: Pope Pius XII, a.k.a. Cardinal Pacelli succeeds Pope Pius XI as the 258th pope.
- April 3: President Roosevelt signs the Reorganization Act of 1939 inaugurating administrative reforms.
- May 17: British government publishes White Paper articulating policy to limit Jewsih immigration to British League of Nations Mandate Palestine.
- June 4: SS St. Louis carrying 907 Jewish refugees is denied permission to land in Florida after already having been turned away from Cuba. Most of the passengers are killed in German concentration camps after their return.
- July 24: British Parliament passes the Prevention of Violence Bill allowing registration of all Irish in Britain and their summary deportation.
- July 26: IRA bombing at King's Cross Station kills one and wounds 15. This the 127th IRA bombing of the campaign.
- August 1939: Pres. Roosevelt reads 495 word letter from exile physicist Leo Szilard persuading him to begin the Manhattan Project.
- August 25: IRA bombing in a Coventry shopping center kills 5 and wounds 50.
- August 25: Canadian Militia are mobilzed in response to the deepening crisis in Europe.
- September 1: Germany invades Poland. The United Kingdom and France declare war on Adolf Hitler's Germany to begin World War II. Canada mobilizes the Canadian Active Service Force.
- September 1: First Cannes Film Festival; the second doesn't happen until 1946.
- September 3: Britain enters Second World War. IRA ends its bombing campaign.
- September 10: Canada declares war on Germany.
- September 25: German Luftwaffe bombs Warsaw.
- November 9: Unsuccessful assassination attempt against Adolf Hitler at the annual Beer Hall Putsch Celebration.
- December 6: Gen. Fulgencio Batista resigns his Army commission to reun for President of Cuba as citizen Batista.