1917

1845–1958	Germany [earth sciences]	German naturalist and explorer Alexander von Humboldt lays the basis of modern geography with the publication of Kosmos/Cosmos, in which he arranges geographic knowledge in a systematic fashion.
1917	United Kingdom [clothing and fashion]	The need for British women to cut their hair short for war work in the factories leads to a fashion for the bob.
1917	[fiction]	The English writer P G Wodehouse publishes The Man with Two Left Feet, a collection of stories in which his comic characters Jeeves and Wooster first appear.
1917	USA [food and drink]	The US inventor Clarence Birdseye develops a rapid freezing method of preserving food that also preserves its flavour.
1917	USA, Europe [cinema and film]	The cinema is becoming a more popular pastime among the middle classes in the USA and in Europe with the advent of better-quality films and the need for diversion during the war.
1917	USA [cinema and film]	Dr Herbert Kalmus makes the first successful use of the Technicolor film process, which he invented in 1915. The Gulf Between is the first technicolor film.
1917	USA [motor vehicles]	There are 4,842,139 motor vehicles registered in the USA, including more than 435,000 trucks, over half of world total.
1917	[painting]	The Italian artist Giorgio de Chirico paints Disquieting Muses.
1917	[philosophy]	Italian philosopher Benedetto Croce publishes Teoria e storia della storiografia/History: Its Theory and Practice.
1917	[poetry]	The Irish writer W B Yeats publishes his poetry collection The Wild Swans at Coole, which includes ‘An Irish Airman Foresees his Death’.
1917	United Kingdom [postal services]	The postal district codes in London, England, are further classified by the addition of postal numbers.
1917	[solo and chamber music]	The French composer Maurice Ravel completes his piano work Le Tombeau de Couperin/The Tomb of Couperin, which he orchestrates in 1919.
1917	[technology]	The US inventor Edwin Armstrong invents the superheterodyne radio circuit. It allows easy tuning of weak radio waves, which it also amplifies. Its design becomes the basis of radar, television, and all amplitude modulation (AM) radios.
1917	United Kingdom, Germany [trade]	German submarine blockades of shipping lead to food shortages in Britain.
1 February 1917	Germany [World War I (1914–18)]	Germany announces its return to a policy of unrestricted submarine warfare in order to cut off the supplies sent to the Allies from the British Empire and the USA.
1 March 1917	USA, Mexico, Germany [World War I (1914–18)]	The publication in the USA of the ‘Zimmermann telegram’ causes outrage. The telegram is a message from the German foreign minister Arthur Zimmermann to the German ambassador in Mexico City, Mexico, which states that if war breaks out between Germany and the USA, the ambassador is to propose an alliance with Mexico and support Mexico's reacquisition of territory lost to the USA in 1848.
4 March - 5 April 1917	Germany, France [World War I (1914–18)]	German troops withdraw to the specially constructed ‘Hindenburg Line’ on the Western Front. The line is a defensive system in which weak points found in the previous front line have been avoided.
8 March - 15 March 1917	Russian Empire [Russian Revolution]	The ‘February Revolution’ takes place in Russia, striking workers being joined on 10 March by soldiers. On 14 March the duma (parliament) establishes a provisional government headed by Prince George Lvov. The revolution is called the ‘February Revolution’ on the basis of the old Julian calendar, under which the revolution takes place in the period 23 February–2 March.
15 March 1917	Russian Empire [political events]	Tsar Nicholas II of Russia abdicates the throne on behalf of both himself and his son. His brother Grand Duke Michael refuses the throne on 16 March, thereby ending the rule of the Romanov dynasty.
2 April 1917	USA [World War I (1914–18)]	The US president Woodrow Wilson calls a special session of the US Congress to debate a declaration of war against Germany, telling Congress ‘The world must be made safe for democracy’. The Senate votes 82–6 to declare war on Germany and the House of Representatives votes 373–50 in favour.
16 April - 9 May 1917	France [World War I (1914–18)]	The French commander General Robert Nivelle launches the ‘Chemin des Dames’ offensive (or Second Battle of the Aisne) along the River Aisne. The French forces make tiny advances at heavy cost.
17 April 1917	France [World War I (1914–18)]	The first in a wave of French army mutinies occurs on the Western Front in protest at the ‘Chemin des Dames’ offensive. A more serious mutiny begins on 29 April, and such mutinies continue until August 1917, ending the French army's capacity to mount offensives.
15 May 1917	France [law and government]	Following the mutinies in response to the costly ‘Chemin des Dames’ offensive, General Robert Nivelle is dismissed as commander in chief of the French army and is replaced by Henri Pétain, who is renowned for using his troops sparingly. Ferdinand Foch replaces Pétain as chief of the general staff.
18 May 1917	Russian Empire [law and government]	Prince George Lvov reforms the cabinet of the Russian provisional government with representation by socialists, and Alexander Kerensky becomes minister of war.
29 May 1917	[births and deaths]	John F Kennedy, 35th president of the USA 1961–63, a Democrat, born in Brookline, Massachusetts (–1963).
12 June 1917	Greece [law and government]	Following threats of invasion from the Allies, the pro-German King Constantine I of Greece abdicates in favour of his second son, Alexander (–1920).
18 June - 13 July 1917	Russian Empire [World War I (1914–18)]	The Russian minister of war, Alexander Kerensky, launches the Kerensky Offensive on the Eastern Front with a series of attacks against the German armies, which are quickly repulsed with heavy Russian losses.
2 July - 5 July 1917	USA [civil rights]	A race riot erupts in East St Louis, Missouri, where alienated white workers rampage through black neighbourhoods killing any black American in sight. ‘Official’ figures list 39 black and 8 white people killed, but civil-rights leader W E B Du Bois insists that as many as 125 people have died in what is undoubtedly the worst racial pogrom in US history.
16 July - 17 July 1917	Russian Empire [Russian Revolution]	During mass demonstrations in Petrograd, Russia, known as the ‘July Days’, the provisional government is undermined, but an attempted Bolshevik rising fails after details emerge of the dealings between the Bolshevik leader Vladimir Ilyich Lenin and Germany, who had helped him return to Russia.
19 July 1917	Germany [law and government]	The SPD, Centre Party, and Progressives in the German Reichstag (parliament) combine to pass a motion demanding peace with no annexations or indemnities.
31 July - 6 November 1917	Belgium, United Kingdom [World War I (1914–18)]	The Third Battle of Ypres (the Battle of Passchendaele) takes place on the Western Front. British forces in Belgium advance about 13 km/8 mi, but at a heavy cost in casualties.
9 September - 14 September 1917	Russian Empire [Russian Revolution]	General Lavr Kornilov attempts a counter-revolutionary coup but is prevented from reaching Petrograd, Russia, by Bolshevik railwaymen. Kornilov is later arrested.
27 September 1917	[births and deaths]	Edgar Degas, French artist known for his paintings, drawings, and bronzes of the human figure in motion, dies in Paris, France (83).
24 October - 26 December 1917	Italy [World War I (1914–18)]	At the Battle of Caporetto, Italy, the Austro-Hungarian and German forces under General Otto von Below break the Italian line and advance 16 km/10 mi. The Italian army regroups along the River Piave.
28 October 1917	Italy [law and government]	Vittorio Orlando becomes Italian prime minister following the major military defeat at Caporetto, and establishes a Unione Sacra coalition government which keeps Italy in the war.
1 November 1917	Germany [law and government]	Count Georg von Hertling succeeds George Michaelis as German chancellor when the latter fails to quell the pro-peace lobby.
2 November 1917	United Kingdom, Palestine, Ottoman Empire [political events]	The British foreign secretary, Arthur Balfour, issues the ‘Balfour declaration’ on Palestine, in which he favours the establishment of a national home for the Jewish people without prejudice to non-Jewish communities.
6 November 1917	Russia [Russian Revolution]	The ‘October Revolution’ takes place in Russia, Vladimir Ilyich Lenin and the Bolsheviks seizing the Winter Palace in Petrograd, Russia, on 7 and 8 November and overthrowing the provisional government. The revolution is named after the date on which it commences under the old Julian calendar (24 October).
16 November 1917	France [law and government]	Paul Painlevé falls as prime minister of France amid fears of French capitulation in the European war, and the aggressive Georges Clemenceau (‘the tiger’) forms a cabinet.
17 November 1917	[births and deaths]	Auguste Rodin, French sculptor renowned for his realistic treatment of the human figure, dies in Meudon, France (77).
20 November - 7 December 1917	France [World War I (1914–18)]	The Battle of Cambrai takes place in northeastern France and is the first major battle involving tanks. A British tank force breaks the German line at Cambrai, but their success is not exploited.
5 December 1917	Germany, Russia [treaties]	German and Russian delegates sign an armistice at Brest-Litovsk (in modern Belarus).
8 December 1917	Estonia [political events]	Bolshevik rule is established in Estonia under the communist leader Jaan Anvelt; it lasts only until the German occupation of the country in February 1918.
9 December 1917	Romania, Germany, Austria-Hungary [treaties]	Romania signs an armistice with the Central Powers at Focsani, Romania.