World War II Timeline: 1940
Explore 27 documented milestones from 1940, across military theaters, diplomacy, society and technology.
Dated historical records
Entries below follow the dates recorded in the WWII CHRONOS archive. Each linked title opens the original historical entry, including its source reference.
- — High-Power Cavity Magnetron Successfully Tested in Birmingham — The technological foundation for compact microwave radar.
- — Russell Ohl Observes the p–n Junction in Silicon — A fundamental milestone for the future semiconductor industry.
- — Moscow Peace Treaty with Finland — The Winter War ends with a peace treaty under which Finland cedes territory to the Soviet Union.
- — Invasion of Denmark and Norway — Germany begins an operation to occupy two Scandinavian states.
- — First Naval Battle of Narvik — British destroyers attacked German ships in Narvik harbour.
- — Second Naval Battle of Narvik — A British force again attacked German destroyers in the Norwegian fjords.
- — Allied Landing at Namsos — British and French forces began landing in central Norway.
- — Allied Withdrawal from Central Norway — British command begins withdrawing troops from the Trondheim area.
- — Sealing of the Łódź Ghetto — The German administration isolated the city's Jewish population.
- — German Offensive in France and the Benelux — German forces attack the Netherlands, Belgium, Luxembourg and France.
- — Capitulation of the Netherlands — On 10 May 1940, German forces launched an offensive against the Netherlands as part of the wider attack on Western Europe.
- — Nylon Stockings Go on Mass Sale — Synthetic fibres enter the mass consumer market.
- — Evacuation from Dunkirk — The Allies begin evacuating a large number of troops across the English Channel.
- — Allies Recapture Narvik — Norwegian and Allied forces regain control of Narvik.
- — Italy Enters the War — Mussolini's regime declares war on France and Britain.
- — Soviet Ultimatum to Lithuania — The Soviet Union presented Lithuania with an ultimatum that was followed by Soviet occupation of the country.
- — French Armistice with Germany — After France's defeat, an armistice is signed; a large part of the country comes under occupation.
- — Romania Agrees to Cede Bessarabia and Northern Bukovina — In June 1940, the Soviet Union issued Romania an ultimatum demanding Bessarabia and the northern part of Bukovina.
- — Battle of Britain — The Luftwaffe begins a major air campaign against Britain.
- — First Flight of the Caproni Campini N.1 Experimental Jet Aircraft — One of the earliest full-scale demonstrations of jet propulsion.
- — Marl Plant Produces Its First Bales of Buna Synthetic Rubber — Initial annual capacity: approximately 18,000 t.
- — Beginning of the London Blitz — German aircraft begin a series of mass raids on London.
- — Bell Labs Publicly Demonstrates Remote Computing over Telephone Lines — An early demonstration of remote access to a computing machine.
- — American Bantam Delivers the First Prototype of the Future Jeep — 49 days elapsed from order to prototype delivery.
- — Tripartite Pact — Germany, Italy and Japan formalise a military-political alliance.
- — Italian Invasion of Greece — Italian forces invade Greece from occupied Albania.
- — Warsaw Ghetto Sealed — The German occupation authorities isolate Jews inside the Warsaw ghetto.
For wider context, explore the interactive historical timeline and compare events across theaters.