- Sep 2 Great Smoky Mountains National Park dedicated
PGA Men's Championship
Sep 2 PGA Championship Men's Golf, Hershey CC: Byron Nelson wins his first PGA C'ship, beating Sam Snead 1 up in the Monday 36-hole final
- Sep 3 39.4 cm rainfall at Sapulpa, Oklahoma (state record)
Operation Sealion
Sep 3 Adolf Hitler orders an invasion of Great Britain for Sept 21 (Operation Seelöwe/Sealion)
- Sep 3 Dutch government in exile of Gerbrandy forms in London
- Sep 3 Sicherheits police bans Free masons, Rotary & Red Cross
- Sep 3 US gives Britain 50 destroyers in exchange for Newfoundland base lease
- Sep 4 CBS begins broadcasting TV as station W2XAB
- Sep 4 Gerbrandy becomes premier of Dutch government in exile
- Sep 4 Nazi collaborator Anton Mussert puts the fate of Netherlands in Hitler's hands
- Sep 6 Crown prince Michael succeeds Carol II as king of Romania
- Sep 6 Former French Commander-in-Chief Army General Maurice Gamelin and other military leaders arrested for their malfeasance [1]
'Hitler Will Have to Break Us or Lose the War'
Sep 7 Beginning of the Blitz as the German Luftwaffe bomb London for the 1st of 57 consecutive nights losing 41 bombers as the Nazis prepare to invade Britain
- Sep 7 Treaty of Craiova: Romania loses Southern Dobrudja to Bulgaria
- Sep 9 28 German aircraft shot down above England
US Men's Tennis Open
Sep 9 US National Championship Men's Tennis, Forest Hills, NY: Donald McNeill beats fellow American Bobby Riggs 4-6, 6-8, 6-3, 6-3, 7-5 for his second major singles title
US Open Women's Tennis
Sep 9 US National Championship Women's Tennis, Forest Hills, NY: Defending champion Alice Marble beats Helen Jacobs 6-2, 6-3 for her third US singles title
- Sep 10 Buckingham Palace hit by German bomb in London
- Sep 11 -12] Buckingham Palace damaged by German bombs
- Sep 11 54th US Postmaster General: Frank C. Walker of Pennsylvania takes office
- Sep 11 Anton Mussert establishes Dutch SS
- Sep 11 George Stibitz pioneers the first remote operation of a computer
- Sep 11 Nazi Germany begins Operation Seelöwe (Sealion - aborted invasion of England)
- Sep 12 49 die & 200 injured when Hercules Powder Co plant explodes u in New Jersey
Dog Unearths Cave of Antiquity
Sep 12 Four teens, following their dog down a hole near Lascaux, France and discover 17,000 year old drawings now known as the Lascaux Cave Paintings
- Sep 12 Italian troops enter Egypt
- Sep 13 Buckingham Palace damaged by German bombs
- Sep 13 Italian troops under Marshal Graziani attack Egypt
- Sep 14 German bomb hits shelter in Chelsea; hundreds die
- Sep 14 US Congress passes 1st peace-time conscription bill (draft law)
- Sep 15 3rd American Football League plays 1st game (Milw 14, Columbus 2)
- Sep 15 Battle of Britain Day: climax of the Battle of Britain, tide begins to turn as the Royal Air Force repulses a major Luftwaffe attack, losing 29 aircraft to the Germans' 57-61
- Sep 15 Chicago Tribune sponsors Ted Lyons Day (White Sox pitcher)
Battle of Britain's Fierest Day
Sep 15 UK Prime Minister Winston Churchill visits Royal Air Force 11th Fighter Group on what would be the fiercest day of the Battle of Britain
Leo Durocher Suspended
Sep 16 Leo Durocher suspended from Ebbetts Field for "inciting a riot"
- Sep 16 Luftwaffe attacks central London
- Sep 16 Samuel Rayburn of Texas elected speaker of US House of Representatives
- Sep 16 St Louis Browns Johnny Lucadello is 2nd to HR from each side of plate
- Sep 17 Adolf Hitler indefinitely postpones Operation Sealion, the planned German invasion of Great Britain
- Sep 17 Nazis deprive Jews of possessions
- Sep 18 19 German aircraft shot down above England
- Sep 18 Elmer Harris' "Johnny Belinda" premieres in NYC
- Sep 18 Italian troops conquer Sidi Barrani
- Sep 19 Nazi decree forbids gentile woman to work in Jewish homes
Pilecki Volunteers for Auschwitz
Sep 19 Witold Pilecki is voluntarily captured and sent to Auschwitz in order to smuggle out information and start a resistance
- Sep 23 -27] French/British assault on French fleet in Dakar, flees
Mondrian Leaves Europe
Sep 23 Dutch artist Piet Mondrian leaves Europe for New York, where he lives for the rest of his life
- Sep 23 Dutch Nazi collaborator Mussert's 1st meeting with Adolf Hitler
- Sep 24 Jimmy Foxx hits his 500th career HR
- Sep 24 Luftwaffe bombs Spitfire factory in Southampton
Vidkun Quisling Government
Sep 25 German High Commissioner in Norway sets up Vidkun Quisling government
Floyd Giebell's 1st Game
Sep 27 MLB Detroit Tigers rookie pitcher Floyd Giebells throws 2-0 shut-out over Cleveland Indians Bob Feller to clinch the AL pennant at League Park in Cleveland, Ohio
- Sep 27 Nazi Germany, Italy & Japan sign 10 year formal alliance (Axis)
- Sep 27 Yankees, lose to A's & eliminated from pennant for 1st time since 1935
Fan Tackles Tom Harmon
Sep 28 Bud Brennan, a fan at Memorial Stadium, races out of stands and attempts to tackle Tom Harmon at 3-yard line, Harmon easily evades
- Sep 28 Michigan's Tom Harmon runs 72, 86 & 94 yard touchdowns
- Sep 28 Nazi occupiers present "New Dutch Culture" in German
- Sep 29 "Double or Nothing", a radio quiz show, 1st heard on Mutual Radio Net
SS Booker T. Washington
Sep 29 1st US merchant ship "Booker T. Washington" commanded by a black captain (Hugh Mulzac), launched at Wilmington Delaware
Strike Up the Band
Sep 29 Musical film "Strike Up the Band" starring Mickey Rooney and Judy Garland opens
- Sep 30 47 German aircraft shot down above England
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