World war II timeline - September 1940

2 September 1940	The US and Great Britain sign a deal in which the US will gain the lease of naval and air bases in Newfoundland, islands of Bermuda, Bahamas, Jamaica, St. Lucia, Trinidad, Antigua, and British Guiana, in exchange for fifty naval destroyers.
3 September 1940	Hermann Göring decides to cease bombing British airfields, switching to bombing London. Adolf Hitler postpones an invasion of Great Britain until September 21.
4 September 1940	Adolf Hitler announces that British cities will be bombed night after night, in retaliation for their bombing of Berlin. In Japan, a meeting is held of four principal ministers to establish guidelines for negotiating joining an alliance with Germany and Italy. They establish that Japan's sphere of influence would encompass China, Manchuria, former German-mandated islands, French Indochina and Pacific islands, Siam, British Malaya and Borneo, Netherlands East Indies, Burma, Australia, New Zealand, and possibly India.   German submarines in the Atlantic begin using "wolf pack" tactics in hunting shipping targets. Three submarines attack 53 ships in Convoy CS-2. Six ships are sunk.
6 September 1940	Since August 23, British fighter plane losses (destroyed or damaged) total 466; German aircraft losses total 352.
7 September 1940	British bomber planes begin bombing English Channel invasion ports and barges on the continent. 625 German bombers and 648 fighters fly up the Thames River, bombing docks, central London, and the East End. Civilian casualties are 300 dead, 1300 wounded. Repeated waves of attacks continue until 0500 hours the next day. The British government announces that a German invasion is imminent. The codeword "Cromwell" is passed nation-wide, and church bells ring out in warning that a German invasion may be underway.
8 September 1940	A heavy German air raid on London is repulsed by British fighter planes.
9 September 1940	Britain renews its guarantee against external aggression to Greece.
11 September 1940	Adolf Hitler postpones invasion of Great Britain to September 24.
12 September 1940	Canada's cabinet introduces Order In Council P.C. 4751, giving Canadian authorities power to imprison disobedient foreign seamen from non-Canadian ships in Canadian ports.
13 September 1940	The Italian 10th Army of over 200,000 men, commanded by Marshal Graziani, crosses the Libyan frontier into Egypt, to gain control of the Suez Canal. They venture fifty miles in, and set up defences at Sidi Barrani. This act begins the war in North Africa. The Japanese Foreign Minister Yosuke Matsuoka and German aide to Ribbentrop Heinrich Stahmer reach a general agreement for a joint alliance.
15 September 1940	In the mid-Atlantic, south-east of Iceland, a submarine sinks Canadian merchant ship Kenordoc en route to Bristol, England. During the day, Germany sends 1700 planes against Britain. Eighty are shot down, with British losses of 35 fighters. (Adolf Hitler is convinced an invasion of England is impossible at this time, due to the lack of air superiority. This day marks the climax of the Battle of Britain.) In the United States, Congress authorizes nationwide conscription. British aircraft carrier Argus delivers twelve Hurricane fighters to Malta. In London, England, Buckingham Palace is hit by aerial bombs. Adolf Hitler gives instruction that "No hint of Operation Barbarossa must be given to the Japanese". British Ministry of Supply asks if Canada will build a poison gas factory to produce phosgene.
16 September 1940	Spanish Minister of the Interior Serrano Suñer visits Berlin, Germany, for negotiations on Spain's joining the Axis in war. Germany wants one of the Canary Islands, a German base in French Morocco (if gained by Spain), and influence in Spain's economy. The terms are unacceptable.
17 September 1940	Adolf Hitler gives orders to postpone indefinitely invasion plans of Great Britain. The invasion fleet and troops are ordered dispersed from the area.
18 September 1940	Soviet Minister of Defence Marshal S.K. Timoshenko and Chief of General Staff K.A. Meretskov submit a war plan to Josef Stalin and Prime Minister Vyacheslav Molotov, proposing an attack on Germany north of the Pripet marshes, with a strong defence to the south, or vice-versa.
19 September 1940	Japan notifies Indochina that their forces would cross the border.
20 September 1940	In Canada, the War Technical and Scientific Development Committee approves a request by Frederick Banting to begin bacterial warfare research.
21 September 1940	Over the past 17 days, British aircraft have sunk 12.5% of 1865 German transport vessels preparing for an invasion of England.
23 September 1940	Japanese forces march into northern French Indochina, taking Tonkin Province quickly. British and Free French forces commence a joint operation under Charles de Gaulle to try to seize Dakar in French West Africa. 119 British bombers attack Berlin, Germany.
25 September 1940	In Norway, the King of Norway and the Administrative Council are deposed, the government is declared illegal, and political parties are dissolved except for the Nasjonal Samling, with Vidkun Quisling as Prime Minister. Royal Canadian Navy armed merchant cruiser Prince Robert captures German merchant ship Weser off Manzillo, Mexico. Operation Menace ends at Dakar in French West Africa, as the occupation force withdraws at night.
26 September 1940	US President Franklin Roosevelt imposes an embargo on the export of aviation fuel, scrap iron, and steel to Japan, citing American defence needs.
27 September 1940	In Berlin, Germany, Japanese premier Prince Fumimaro Konoye and Italian and German officials sign the Tripartite Pact defensive alliance. Each nation pledges mutual support in the event of attack by a power not presently involved in the European or Chinese-Japanese conflict. The intent is to keep the United States out of the war.
28 September 1940	Great Britain receives fifty old destroyers from the USA for use as convoy escorts. British merchant ship MV Automedon sails from London, England, heading to Singapore, carrying most secret and highest level documents, operational plans for the Far East, the Chiefs of Staff assessment of Britain's poor ability to defend Malaya, and British maritime code-books. (In November, the ship is captured by a German ship before the sensitive cargo can be destroyed. Britain assumes it was torpedoed; Germans pass the information to Japan.)