1915

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.
1915	[fiction]	The US writer Willa Cather publishes her novel The Song of the Lark.
1915	[fiction]	The English writer Ford Madox Ford publishes his novella The Good Soldier.
1915	[fiction]	The English writer D H Lawrence publishes his novel The Rainbow.
1915	[fiction]	The Bohemian-born German writer Franz Kafka publishes his novella Die Verwandlung/Metamorphosis.
1915	United Kingdom [food and drink]	The British confectionery company Cadbury's launches Cadbury's Milk Tray chocolates.
1915	United Kingdom [administration]	The inclusion of photographs in passports is made compulsory in Britain.
1915	Russian Empire [aircraft]	Russian engineer Igor Sikorsky builds a 16-passenger biplane. Passengers are in an enclosed cabin and the aeroplane is powered by four 100-horsepower Mercedes engines. It is the first multi-engine aeroplane.
1915	USA [cinema and film]	Dr Herbert Kalmus develops the Technicolor film process in the USA. It will not be commercially viable until the 1930s.
1915	[communications]	US physicist Manson Benedicks discovers that a germanium crystal can convert alternating current to direct current. This leads to the field of solid-state electronics, in the late 1940s.
1915	Germany [medicine]	The German company Bayer introduces aspirin in tablet form.
1915	[orchestral music]	The US composer Charles Ives completes his Orchestral Set No. 2 and his Piano Sonata No. 2, Concord Massachusetts 1840–1860, which includes solos for viola and flute.
1915	[orchestral music]	The Finnish composer Jean Sibelius completes the first version of his Symphony No. 5.
1915	USA [consumer products]	US researchers Eugene C Sullivan and William C Taylor at the Corning Glass Works create Pyrex, a heatproof and shockproof kitchenware.
1915	United Kingdom [women's rights]	Women in wartime Britain are increasingly taking on men's responsibilities in the workplace, and are proving more productive in many fields.
January 1915	Germany, France [weapons]	Germany uses chlorine gas against the Russians. It is the first use of chemical warfare, but it has little effect. On 22 April, however, they use it at the Battle of Ypres to rout French and Canadian troops.
24 January 1915	Germany, United Kingdom [World War I (1914–18)]	In the Battle of Dogger Bank in the North Sea, a British force under Admiral Sir David Beatty sinks the German cruiser Blücher.
3 February 1915	Poland, Russian Empire, Germany [World War I (1914–18)]	The German army uses poison gas at Bolimov, Poland, on the Eastern Front. It is the first time that they have used poison gas on a significant scale.
4 February 1915	United Kingdom, Germany [World War I (1914–18)]	Germany declares the establishment of a submarine blockade around Britain from 18 February, and declares that any foreign vessel found in the area will be considered a legitimate target.
7 February - 21 February 1915	Russian Empire, Germany, Austria-Hungary [World War I (1914–18)]	In the Winter Battle of Masuria on the Eastern Front, the German and Austro-Hungarian armies force the Russian troops to retreat.
8 February 1915	[cinema and film]	The film Birth of a Nation, directed by D W Griffith, is released in the USA. An influential and commercially successful silent film, it stars Lillian Gish, Mae Marsh, and Henry B Walthall. Its epic scope and innovative cinematic techniques are, however, marred by racism, which includes a sympathetic portrayal of the Ku Klux Klan.
22 March 1915	Poland, Russian Empire [World War I (1914–18)]	Russian forces take Przemysl in the Polish area of northeastern Austria-Hungary (a key strategic point in the Carpathian Mountains) after a siege of 194 days.
7 April 1915	[births and deaths]	Billie Holiday (real name Eleanora Fagan), US jazz singer, born in Baltimore, Maryland (–1959).
22 April - 25 May 1915	Belgium [World War I (1914–18)]	At the Second Battle of Ypres, Belgium, a German counteroffensive pushes the Western Front in southwestern Belgium forward by 5 km/3 mi.
24 April 1915	Armenia, Ottoman Empire [World War I (1914–18)]	The wartime deportation and massacre of Armenians accused of collaborating with the Allies begins in the Ottoman Empire. 1.75 million people are driven across the Mesopotamian desert, over a million of them dying in the process.
26 April 1915	United Kingdom, France, Italy [World War I (1914–18)]	Britain, France, and Italy make the secret Treaty of London, under which Italy will join the war in return for land and reparations from Germany and Austria-Hungary when the war ends.
2 May - 19 September 1915	Austria-Hungary [World War I (1914–18)]	An Austro-German offensive begins in Galicia (northeastern Austria-Hungary) with the Battle of Gorlice-Tarnów, breaking the Russian lines.
6 May 1915	[births and deaths]	Orson Welles, US film actor, director, producer, and writer, best known for Citizen Kane, born in Kenosha, Wisconsin (–1985).
9 May - 18 June 1915	France [World War I (1914–18)]	At the Second Battle of Artois in France, the French armies under General Henri Pétain push forward in northeastern France, but gain little ground in spite of diversionary British attacks.
3 June 1915	Poland, Russian Empire [World War I (1914–18)]	The Russian southern front collapses when German forces recapture Przemysl, Poland.
23 June - 7 July 1915	Italy [World War I (1914–18)]	The First Battle of the Isonzo takes place when an Italian army under General Luigi Cadorna tries to force bridgeheads on the River Isonzo at Gorizia and Tolmino in Italy, an area held by Austrian forces led by Archduke Eugene.
9 July 1915	German South West Africa [World War I (1914–18)]	German forces in South West Africa surrender to the South African Louis Botha.
September 1915	United Kingdom [weapons]	The armoured car division of the British Royal Naval Air Service introduce ‘Little Willie’, the first purpose-built tank. A second model, ‘Big Willie’, is introduced shortly afterwards.
11 September 1915	United Kingdom [companies and organizations]	The first Women's Institute is set up, in Anglesey, Wales.
25 September - 15 October 1915	France [World War I (1914–18)]	At the Third Battle of Artois, French forces attack the German line in northeastern France and in Champagne to the southeast, while a British force, using gas for the first time, attacks the line at Loos on 4 November. Only small gains are made.
14 October 1915	Bulgaria [World War I (1914–18)]	Bulgaria enters the war on the side of the Central Powers.
November 1915	USA [human rights]	The Ku Klux Klan, a racist society that originated in the 1860s, is revived by William Joseph Simmons near Atlanta, Georgia, dedicated to ‘white supremacy’ and ‘Americanism’. Within six years it attracts a membership of nearly 100,000.
12 November 1915	Pacific, United Kingdom [colonies and mandate]	Britain annexes the Gilbert and Ellice Islands (modern Tuvalu and Kiribati) in the Pacific Ocean, converting the protectorate into a colony.
22 November - 4 December 1915	Anatolia, Iraq, Ottoman Empire, United Kingdom [World War I (1914–18)]	In the Battle of Ctesiphon, Ottoman troops force the British invaders of Mesopotamia back to Kut-al-Imara, Mesopotamia.
25 November 1915	[births and deaths]	Augusto Pinochet, Chilean president 1973–89, and military dictator, born.
12 December 1915	[births and deaths]	Frank Sinatra, US singer and actor, born in Hoboken, New Jersey.
18 December - 19 December 1915	Anatolia, Ottoman Empire [World War I (1914–18)]	In a highly successful evacuation, Allied troops withdraw from Suvla Bay and Anzac Cove on the Gallipoli Peninsula following the failure of the Dardanelles campaign.