Date Event
August 23 1939 Molotov-Ribbentrop Pact is signed between Germany and Soviet Union.
September 1 1939 The Invasion of Poland begins at 4:30 a.m. with the German Luftwaffe attacking several targets in Poland. The United Kingdom and France demand Germany's immediate withdrawal.

The United Kingdom home front is opened as the government declares general mobilization of the British Army and begins evacuation plans in preparation of German air attacks.

September 3 1939 France and Great Britain declare war on Germany after German refusal to withdraw from Poland.
September 4 1939 Royal Air Force (RAF) Bomber Command launches a raid on the German Admiral Scheer in the Heligoland Bight. Six of the 24 attacking aircraft are lost, and while the German vessel is hit three times, all of the bombs fail to explode.
September 7 1939 French patrols enter Germany near Saarbrücken.
September 9 1939 Canada declares war on Germany.
September 17 1939 The Soviet Union invades Poland from the east, occupying the territory east of the Curzon line as well as Białystok and Eastern Galicia.
September 18 1939 Warsaw is surrounded by German troops.
September 25 1939 German home front measures begin with food rationing.
September 27- September 28 1939 Extensive bombardments of Warsaw.
September 28 1939 The Polish capital Warsaw surrenders to the Germans.
October 5 1939 The Soviet Union begins talks with Finland to adjust the border between the two countries.
October 6 1939 Polish resistance in the Polish September Campaign comes to an end. Finland begins mobilizing its army; Hitler speaks before the Reichstag, declaring a desire for a conference with Britain and France to restore peace.
October 9 1939 Hitler issues orders to prepare for the invasion of Belgium, France, Luxembourg and the Netherlands.
October 10 1939 The German navy suggests occupying Norway to Hitler.
October 14 1939 The British battleship HMS Royal Oak is sunk in Scapa Flow harbour by U-47.
October 19 1939 Portions of Poland are formally inducted into Germany; the first Jewish ghetto is established at Lublin.
November 30 1939 The Soviet Union invades Finland in what would become known as the Winter War.
December 1 1939 Jews are forced to wear the emblem of the Star of David.
December 7 1939 Italy again declares its neutrality.
December 13 1939 Battle of the River Plate, British naval squadron attacks the Admiral Graf Spee.
December 14 1939 The USSR is expelled from the League of Nations.
December 17 1939 Admiral Graf Spee scuttled in Montevideo harbour.
December 18 1939 The first Canadian troops arrive in Europe.
December 27 1939 The first Indian troops arrive in France.
December 28 1939 Meat rationing program begins in Britain.
February 1 1940 Japanese Diet announces record high budget with over half its expenditures being military.
February 5 1940 Britain and France decide to intervene in Norway to cut off the iron ore trade — in anticipation of an expected German occupation and ostensibly to open a route to assist Finland. The operation is scheduled to start about March 20.
February 9 1940 Erich von Manstein is placed in command of German XXXIII Armor Corps, removing him from planning the French invasion.
February 14 1940 British government calls for volunteers to fight in Finland.
February 15 1940 Soviet army captures Summa in Finland thereby breaking through the Mannerheim Line.
February 16 1940 British destroyer HMS Cossack forcibly removes 299 British POWs from the German transport Altmark in neutral Norwegian territorial waters.
February 17 1940 Manstein presents to Hitler his plans for invading France via the Ardennes forest.
February 21 1940 General Nikolaus von Falkenhorst is placed in command of the upcoming German invasion of Norway; work begins on the construction of Auschwitz.
February 24 1940 The Ardennes plan for invading the west is adopted.
March 3 1940 Soviets begin attacks on Viipuri, Finland's second largest city.
March 5 1940 Finland tells the Soviets they will agree to their terms for ending the war.
March 12 1940 Finland signs a peace treaty with the Soviet Union.
March 16 1940 German air raid on Scapa Flow causes first British civilian casualties.
March 18 1940 Mussolini agrees with Hitler that Italy will enter the war "at an opportune moment".
March 51 1940 Paul Reynaud becomes Prime Minister of France following Daladier's resignation the previous day.
March 28 1940 Britain and France make a formal agreement that neither country will seek a separate peace with Germany.
March 30 1940 Japan establishes a puppet regime at Nanking, China, under Wang Jingwei.
April 3 1940 Churchill is appointed chairman of the Ministerial Defense Committee following the resignation of Lord Chatfield.
April 4 1940 Hitler gives the go ahead for the invasion of Norway and Denmark.
April 5 1940 Chamberlain makes an ill-timed remark that Hitler has "missed the bus".
April 8 1940 Allied mining of Norwegian waters is put into action.
April 9 1940 Germany invades Denmark and Norway; Denmark surrenders.
April 10 1940 First Battle of Narvik, British destroyers and aircraft successfully make a surprise attack against a larger German naval force. A second attack on April 13 will also be a British success.
April 12 1940 British troops occupy the Danish Faroe Islands.
April 14 1940 British and French troops begin landing in Norway.
May 5 1940 Norwegian government in exile established in London.
May 9 1940 Conscription in Britain extended to age 36.
May 10 1940 Germany invades Belgium, France, Luxembourg and the Netherlands; Winston Churchill becomes Prime Minister of the United Kingdom upon the resignation of Neville Chamberlain. The United Kingdom invades Iceland.
May 11 1940 Luxembourg occupied.
May 13 1940 Dutch government in exile established in London.
May 14 1940 The creation of the Local Defense Volunteers (the Home Guard) is announced by Anthony Eden.

Rotterdam is carpet-bombed by the Luftwaffe. The Netherlands decide to surrender with the exception of Zealand.

May 15 1940 The capitulation of the Dutch army is signed.
May 17 1940 In the Netherlands the province of Zealand surrenders.
May 18 1940 Maxime Weygand replaces Maurice Gamelin as commander of the French armed forces.
May 25 1940 Boulogne-sur-Mer surrenders to the Germans.
May 26 1940 Calais surrenders to the Germans.

Operation Dynamo, the Allied evacuation from Dunkirk, begins.

May 28 1940 Belgium surrenders to the Germans; Germans evacuate Narvik.