* 1939 – 1945, the Second Battle of the Atlantic.

Subsequent formalizations were framed as attempts to define " effective calculability " or " effective method "; those formalizations included the Gödel – Herbrand – Kleene recursive functions of 1930, 1934 and 1935, Alonzo Church's lambda calculus of 1936, Emil Post's " Formulation 1 " of 1936, and Alan Turing's Turing machines of 1936 – 7 and 1939.

* 1890 – Anthony Fokker, Dutch aviation engineer ( d. 1939 )

* 1939 – André Ouellet, French-Canadian politician

* 1852 – Ferdinand von Lindemann, German mathematician ( d. 1939 )

* 1939 – Alan Ayckbourn, English writer

* 1939 – Johnny Raper, Australian rugby league footballer

* 1939 – The 1939-40 New York World's Fair opens.

* 1939 – NBC inaugurates its regularly scheduled television service in New York City, broadcasting President Franklin D. Roosevelt's N. Y. World's Fair opening day ceremonial address.

* 1939 – First flight of the turbojet-powered Heinkel He 178, the world's first jet aircraft.

* 1939 – William Least Heat-Moon, American author

* 1939 – Edward Patten, American singer-songwriter and producer ( Gladys Knight & the Pips ) ( d. 2005 )

* 1939 – Bulle Ogier, French actress

* 1939 – Romano Prodi, Italian politician and statesman

* 1939 – Hércules Brito Ruas, Brazilian footballer

* 1939 – Albert Einstein and Leó Szilárd write a letter to Franklin D. Roosevelt, urging him to begin the Manhattan Project to develop a nuclear weapon.

* 1939 – Benjamin Barber, American theorist

* 1939 – Wes Craven, American director

* 1939 – John W. Snow, American politician, 73rd United States Secretary of the Treasury

* 1984 – Marvin Gaye, American singer ( The Moonglows ) ( b. 1939 )

* 2001 – Trinh Cong Son, Vietnamese composer ( b. 1939 )

Eastern European theorists include Pyotr Stolypin ( 1862 – 1911 ) and Alexander Chayanov ( 1888 – 1939 ) in Russia ; Adolph Wagner ( 1835 – 1917 ), and Karl Oldenberg in Germany, and Bolesław Limanowski ( 1835 – 1935 ) in Poland.

* The General Takes Off His Helmet ( 1939 ) in The Queen's Book of the Red Cross

Most Holocaust historians identify six German Nazi extermination camps, all in occupied Poland ; two of them, Chełmno and the Auschwitz II, in the western Polish areas annexed by Nazi Germany ( October 1939 ), four in the General Government area.

* 1940 – In a ceremony held in Berkeley, California, because of the war, physicist Ernest Lawrence receives the 1939 Nobel Prize in Physics from Sweden's Consul General in San Francisco.

In 1939, Gardner joined the Folk-Lore Society ; his first contribution to its journal Folk-Lore, appeared in the June 1939 issue and described a box of witchcraft relics that he believed had belonged to the 17th century " Witch-Finder General ", Matthew Hopkins.

Total native Italian population for Libya was 110, 575 out of a total population of 915, 440 in 1940 ( General Staff War Office 1939, 165 / b ).

* 1939 – Spanish Civil War – Catalonia Offensive: Troops loyal to nationalist General Francisco Franco and aided by Italy take Barcelona.

He was General Secretary ( later Chairman of the Presidium ) of the League of Communists of Yugoslavia ( 1939 – 80 ), and went on to lead the World War II Yugoslav guerrilla movement, the Partisans ( 1941 – 45 ).

General der Flieger Hellmuth Felmy, commander of Luftflotte 2 in 1939, was charged with devising a plan for an air war over the British Isles.

The absence of a strategic bomber force for the Luftwaffe, following General Wever's accidental death in 1936 and the end of the Ural bomber program he fostered before the invasion of Poland, would not be addressed again until the authorization of the Bomber B design competition in July 1939, which sought to replace the medium bomber force with which the Luftwaffe was to begin the war, with more advanced, twin-engined high speed bomber aircraft fitted with pairs of relatively " high-power " engines of 1, 500 kW ( 2, 000 hp ) output levels and upwards each, that would also be able to function as shorter range heavy bombers.

As the situation in Europe escalated into war, the Assembly transferred enough power to the Secretary General on 30 September 1938 and 14 December 1939 to allow the League to continue to exist legally and carry on reduced operations.

In 1939 the Liberals, recognizing that they would have to choose someone with national stature to be president if they wanted to hold onto power, picked General Estigarribia, the hero of the Chaco War who had since served as special envoy to the United States.

* September 9 – WWII: Troops of the Polish Poznan Army under the command of General Kutrzeba open the Battle of the Bzura, the largest and best organized counter-attack mounted by the Polish forces in the campaign of 1939.

Nominated by President Franklin Roosevelt to be Army Chief of Staff, Marshall was promoted to General and sworn in on September 1, 1939, the day German forces invaded Poland.

The company's name was changed to Blackburn Aircraft Limited in 1939, and the company amalgamated with General Aircraft Limited in 1949 as Blackburn and General Aircraft Limited, reverting to Blackburn Aircraft Limited by 1958.

After hearing reports of and witnessing massacres in Poland, Canaris on 12 September 1939 travelled to Hitler's headquarters train, at the time in Upper Silesia, to register his objection to the atrocities ; prior to reaching Hitler he encountered General Wilhelm Keitel whom he informed: " I have information that mass executions are being planned in Poland, and that members of the Polish nobility and the Roman Catholic bishops and priests have been singled out for extermination.

Hayakawa read The Tyranny of Words, then Science and Sanity, and in 1939 he attended a Korzybski-led workshop conducted at the newly organized Institute of General Semantics in Chicago.

He attended the Command and General Staff School at Fort Leavenworth, Kansas, in 1935 and 1936, and the Army War College in 1938 and 1939, after which he was posted to the War Department General Staff.

On 1 July 1939, he was posted to the War Department General Staff in Washington, D. C.

On December 15, 1939, the new Bank Emisyjny was established by the General Government, itself set up by Nazi Germany.

The AK's origins were in the Służba Zwycięstwu Polski ( Service for the Victory of Poland ), which had been set up, just as the joint German & Soviet invasions of Poland were nearing completion, on September 27, 1939, by General Michał Karaszewicz-Tokarzewski.

Seven weeks later, November 17, 1939, on the orders of General Władysław Sikorski, this organization was succeeded by Związek Walki Zbrojnej ( Union for Armed Struggle ), which over two years later, on February 14, 1942, became the AK.