Adolf Hitler launches a massive attack on Poland, with tanks crossing the border and air raids on Warsaw

Spain and Portugal declare that they will maintain their neutrality in the European war that now seems inevitable

Britain and France, receiving no answer from Hitler to their ultimatum over his attack on Poland, declare war on Germany

French troops rush to defend France's border with Germany, along the heavily fortified Maginot Line

A British Expeditionary Force (BEF) of about 150,000 infantry crosses the Channel to help defend France's border with Belgium

In spite of the Axis agreement of 1936, Mussolini declines to bring Italy into the war on Hitler's side

Alan Turing joins the code-breaking team working on Enigma at Bletchley Park

A German U-boat sinks the British aircraft carrier Courageous off the coast of Ireland

Finland, Sweden, Norway and Denmark jointly declare their neutrality

Warsaw falls, after a brave resistance, whereupon Germany and Russia carve up Poland

Nazi murder squads (Einsatzgruppen) kill Poland's elite

A German U-boat sinks the British battleship Royal Oak at anchor in Scapa Flow

Adolf Hitler orders the 'mercy killing' of all those with specified categories of infirmity, beginning with newborn babies and young children

Soviet troops cross the borders of Finland, beginning the brief Russo-Finnish War, in keeping with the secret protocol of the Molotov-Ribbentrop Pact

The Finns win spectacular victories in counter-attacks against the Russian invaders, destroying four Soviet divisions

The USSR is expelled from the League of Nations because of the Soviet invasion of Finland

T.S. Eliot gives cats a poetic character in Old Possum's Book of Practical Cats

English potter Bernard Leach publishes an influential manual, A Potter's Book

Richard Addinsell writes the Warsaw Concerto as music for the film Dangerous Moonlight

British biologists Ernst Chain and Howard Florey develop penicillin as a safe and useful antibacterial drug

Flann O'Brien's The Third Policeman is rejected by numerous publishers before becoming, decades later, his best-known novel

British actors Vivien Leigh and Laurence Olivier marry

Roger Schutz establishes an ecumenical religious order at Taiz&eachute; in France

Radar masts along the coasts of Britain give early warning of German air attacks

An assassin sent by Stalin kills the exiled Trotsky in his home in Mexico City