1: The Republic of China and the Empire of Japan are involved in the early stages of the third year of armed conflict between them during the Second Sino-Japanese War. The war is in what will be known as the "Second Period." The "Second Period" starts in October 1938 and ends in December 1941. This conflict would eventually be swept up into WWII when Japan joins the Axis and China the Allies.
2: The United Kingdom and France issue a joint ultimatum to Germany, requiring German troops to evacuate Polish territory; Italian dictator Benito Mussolini declares the neutrality of his nation; President Douglas Hyde of the Republic of Ireland declares the neutrality of his nation; the Swiss government orders a general mobilization of its forces.
3: At 11:15 a.m. British Standard Time (BST), British Prime Minister Neville Chamberlain announces on BBC Radio that the deadline of the final British ultimatum for the withdrawal of German troops from Poland expired at 11:00am and that "consequently this nation is at war with Germany". Australia, India, and New Zealand also declare war on Germany within hours of Britain's declaration.
3: At 12:30pm BST the French Government delivers a similar final ultimatum; which expires at 3:00pm BST.
3: Within hours of the British declaration of War, SS Athenia, a British cruise ship en route from Glasgow, Scotland to Montreal, Canada is torpedoed by the German submarineU-30 250 miles Northwest of Ireland. 112 passengers and crew members are killed. The "Battle of the Atlantic" begins.
4: At 8:00 a.m. Newfoundland Standard Time (NST), Dominion of Newfoundland declares war on Germany.
4: In the first British offensive action of the War, the Royal Air Force launch a raid on the German fleet in the Heligoland Bight. They target the German pocket-battleship Admiral Scheer anchored off Wilhelmshaven at the western end of the Kiel Canal. Several aircraft are lost in the attack and, although the German vessel is hit three times, all of the bombs fail to explode.
4: Japan announces its neutrality in the European situation. The British Admiralty announced the beginning of a naval blockade on Germany, one of a range of measures by which they waged economic warfare on the Axis Powers
11: Viceroy of India Lord Linlithgow announces to the two houses of the Indian Legislature (the Council of State and the Legislative Assembly) that due to India's participation in the war, the plans for the Federation of India under the Government of India Act 1935 will be indefinitely postponed.
15: The Polish Army was ordered to hold out at the Romanian border until the Allies arrived.
16: The German Army complete the encirclement of Warsaw.
16: The French complete their retreat from Germany, ending the Saar Offensive
17: The Soviet Union invades Poland from the east, occupying the territory east of the Curzon line as well as Białystok and Eastern Galicia.
17: Aircraft carrier HMS Courageous torpedoed and sunk by U-29 on patrol off the coast of Ireland
17: The Imperial Japanese Army launched the attacks on the Chinese city of Changsha, when their forces in northern Jiangxi attacked westward toward Henan.
18: Polish President Ignacy Mościcki and Commander-in-ChiefEdward Rydz-Śmigły leave Poland for Romania, where they are both interned; Russian forces reach Vilnius and Brest-Litovsk. Polish submarine escapes from Tallinn - Estonia's neutrality is questioned by the Soviet Union and Germany.
19: The German and Soviet armies link up near Brest Litovsk.
19: Soviet Union blockades the harbour of Tallinn, the capital of Estonia.
24: Soviet air force violates Estonian airspace. The Estonians negotiate with Molotov in Moscow. Molotov warns the Estonians that if the Soviet Union doesn’t get military bases in Estonia, it will be forced to use "more radical actions".
25: German home front measures begin with food rationing.
25: Soviet air activity in Estonia. Soviet troops along the Estonian border include 600 tanks and 600 aircraft and 160 000 men.
26: Following a massive artillery bombardment, the Germans launch a major infantry assault on the centre of Warsaw.
26: Russian bombers seen in the Tallinn sky.
27: In the first offensive operations by the German Army in Western Europe, guns on the Siegfried Line open up on villages behind French Maginot line.
28: German-Soviet Boundary and Friendship Treaty is signed by Molotov and Ribbentrop. The secret protocol specifies the details of partition of Poland originally defined in Molotov-Ribbentrop Pact (August 23, 1939) and adds Lithuania to the Soviet Union sphere of interest.
28: The remaining Polish army and militia in the centre of Warsaw capitulate to the Germans.
28: Soviet troops mass by the Latvian border. Latvian air space violated.
28: Estonia signs a 10-year Mutual Assistance Pact with the Soviet Union, which allows the Soviets to have 30 000-men military bases in Estonia. As a gift in return Stalin promises to respect Estonian independence.
30: The Czechoslovak government capitulated on 30 September and agreed to abide by the agreement. The Munich Agreement stipulated that Czechoslovakia must cede Sudeten territory to Germany.
30: The German pocket-battleship Admiral Graf Spee sinks its first merchant ship, the British freighter Clement while off the coast of Pernambuco, Brazil.
30: French forces on the French-German border fell back to the Maginot Line in anticipation of a German invasion.
2: Latvian representatives negotiate with Stalin and Molotov. Soviets threaten an occupation by force if they do not get military bases in Latvia.
2: Declaration of Panama is approved by American Republics. Belligerent activities should not take place within waters adjacent to the American continent. A neutrality zone of some 300 miles in breadth is to be patrolled by the U.S. Navy.
3: British forces move to the Belgian border, anticipating a German invasion of the West.
3: Lithuanians meet Stalin and Molotov in Moscow. Stalin offers Lithuania the city of Vilnius (in Poland) in return for allowing Soviet military bases in Lithuania. The Lithuanians are reluctant.
5: Latvia signs a 10-year Mutual Assistance Pact with the Soviet Union, which allows the Soviets to have 25,000 men in military bases in Latvia. Stalin promises to respect Latvian independence.
6: Polish resistance in the Polish September Campaign comes to an end. Hitler speaks before the Reichstag, declaring a desire for a conference with Britain and France to restore peace.
7: Lithuanians again meet the Soviets in Moscow. The Soviets demand military bases.
9: Germany issues orders (Case Yellow) to prepare for the invasion of Belgium, France, Luxembourg, and the Netherlands.
10: The last of Poland's military surrenders to the Germans.
10: The leaders of the German navy suggest to Hitler they need to occupy Norway.
10: British Prime Minister Chamberlain declines Hitler's offer of peace.
10: Lithuania signs a 15-year Mutual Assistance Pact with the Soviet Union, which allows the Soviets to have 20,000 men in military bases in Lithuania. In a secret protocol, Vilnius is made Lithuanian territory.
11: An estimated 158,000 British troops are now in France.
12: Adolf Eichmann begins deporting Jews from Austria and Czechoslovakia into Poland.
12: Finland's representatives meet Stalin and Molotov in Moscow. Soviet Union demands Finland gives up a military base near Helsinki and exchange some Soviet and Finnish territories to protect Leningrad against Great Britain or the eventual future threat of Germany.
1: Russia continues its war against Finland; Helsinki is bombed. In the first two weeks of the month, the Finns retreat to the Mannerheim line, an outmoded defensive line just inside the southern border with Russia.
2: British conscription is increased to cover men from 19 to 41.
5: The Russian invaders start heavy attacks on the Mannerheim line.
7: Italy again declares its neutrality. Norway, Sweden, and Denmark also proclaim their neutrality in the Russo-Finnish quarrel.
11: The Russians meet with several tactical defeats by the Finnish army.
12: The destroyer HMS Duchess sinks after a collision with the battleship HMS Barham off the coast of Scotland with the loss of 124 men.