January 23 – “Dutch War Scare”: Admiral Wilhelm Canaris of the Abwehr leaks misinformation to the effect that Germany plans to invade the Netherlands in February, with the aim of using Dutch air-fields to launch a strategic bombing offensive against Britain. The “Dutch War Scare” leads to a major change in British policies towards Europe.
January 26 – In Paris, French Foreign Minister Georges Bonnet, in response to rumours (which are true) that he is seeking to end the French alliance system in Eastern Europe, gives a speech highlighting his government's commitment to the cordon sanitaire.
January 27 – Adolf Hitler orders Plan Z, a 5-year naval expansion programme intended to provide for a huge German fleet capable of crushing the Royal Navy by 1944. The Kriegsmarine is given the first priority on the allotment of German economic resources.
January 30 – Hitler gives a speech before the Reichstag calling for an "export battle" to increase German foreign exchange holdings. The same speech also sees Hitler's “prophecy” where he warns that if "Jewish financers" start a war against Germany, the "...result will be the annihilation of the Jewish race in Europe".
February 6 – British Prime Minister Neville Chamberlain states in the House of Commons that any German attack on France will be automatically considered an attack on Britain.
February 6 – In a response to Georges Bonnet's speech of January 26, German Foreign Minister Joachim von Ribbentrop, referring to Bonnet’s alleged statement of December 6, 1938 accepting Eastern Europe as being in Germany’s exclusive sphere of influence, protests that all French security commitments in that region are “now off limits”.
March 3 – In Durban, South Africa the Timeless Test begins between England and South Africa, the longest game of cricket ever played. It was abandoned 12 days later, when the English team had to catch the last ferry home.
March 16 – Hungary invades Carpatho-Ukraine; final resistance ends on March 18.
March 17 – British Prime Minister Neville Chamberlain gives a speech in Birmingham, stating that Britain will oppose any effort at world domination on the part of Germany.
March 18 – “Romanian War Scare”: Virgil Tilea, the Romanian Minister in London, spreads false rumours that Romania is on the verge of a German attack.
March 20 – At an emergency meeting in London to deal with the Romanian crisis, French Foreign Minister Georges Bonnet suggests to Lord Halifax that the ideal state for saving Romania from a German attack is Poland.
March 28 – American adventurer Richard Halliburton delivers a last message from a Chinese junk, before he disappears on a voyage across the Pacific Ocean.
March 31 – Neville Chamberlain gives a speech in the House of Commons offering the British "guarantee" of the independence of Poland.
April
April 1 – The Spanish Civil War comes to an end when the last of the Republican forces surrender.
April 3 – Adolf Hitler orders the German military to start planning for Fall Weiss, the codename for the invasion of Poland.
April 14 – At a meeting in Paris, French Foreign Minister Georges Bonnet meets with Soviet Ambassador Jakob Suritz, and suggests that a “peace front” comprising France, the Soviet Union, Great Britain, Poland and Romania would deter Germany from war.
April 18 – The Soviet Union proposes a "peace front" to resist aggression.
May 6 – Carl Friedrich Goerdeler tells the British government that the German and Soviet governments are secretly beginning a rapprochement with the aim of dividing Eastern Europe between them. Goerdeler also informs the British of German economic problems which he states threaten the survival of the Nazi regime, and advises that if a firm stand is made for Poland, then Hitler will be deterred from war.
June 3 – The Soviet government offers its definition of what constitutes "aggression", upon which the projected Anglo-Soviet-French alliance will come into effect. The French Foreign Minister Georges Bonnet accepts the Soviet definition of aggression at once. The British reject the Soviet definition, especially the concept of "indirect aggression", which they feel is too loose a definition and phrased in such a manner as to imply the Soviet right of inference in the internal affairs of nations of Eastern Europe.
June 4 – The St. Louis, a ship carrying a cargo of 907 Jewish refugees, is denied permission to land in Florida after already having been turned away from Cuba. Forced to return to Europe, many of its passengers later die in Nazideath camps during the Holocaust.
June 14 – Tientsin Incident: The Japanese blockade the British concession in Tianjin, China, beginning a crisis which almost causes an Anglo-Japanese war in the summer of 1939.
July 4 – Lou Gehrig gives his last public speech, following his diagnosis of amyotrophic lateral sclerosis (ALS). In it, he states, "Today, I consider myself the luckiest man on the face of the earth."
July 23 – Mahatma Gandhi the spiritual leader from India writes a personal letter to Adolf Hitler addressing him "My friend", requesting to prevent any possible war.
August 25 – Adolf Hitler postpones Fall Weiss for 5 days, due to a message from Benito Mussolini that he will not honor the Pact of Steel if Germany attacks Poland in 1939, and to the failure of Chamberlain's government to fall because of the German-Soviet Non-Aggression Pact.
Wieluń destroyed by Luftwaffe bombing the 1st of September 1939
Common parade of Wehrmacht and Red Army in Brest at the end of the Invasion of Poland. At the center Major General Heinz Guderian and Brigadier Semyon Krivoshein.
September 28 – World War II: Warsaw surrenders to Germany; Modlin surrenders a day later; the last Polish large operational unit surrenders near Kock 8 days later.
November 6 – Hedda Hopper's Hollywood debuts on radio with Hollywood gossip columnist Hedda Hopper as host (the show runs until 1951, making Hopper a powerful figure in the Hollywood elite).
November 17 – To punish protests against the Nazi occupation of the Czech homeland, the Nazis murder 9 Czech graduate students, send over 1200 to concentration camps, and close all Czech universities.