1920January 1920 January 1 Polish–Soviet War in 1920: The Russian Red Army increases its troops along the Polish border from 4 divisions to 20. Kauniainen, completely surrounded by the city of Espoo, secedes from Espoo as its own market town. January 3 – The 1920 Xalapa earthquake in Mexico kills over 600 people, making it the second deadliest in the country. January 7 – Russian Civil War: The forces of Russian White Admiral Alexander Kolchak surrender in Krasnoyarsk; the Great Siberian Ice March ensues.
1916Below, the events of the First World War have the "WWI" prefix. January 1916 January 1 – The British Royal Army Medical Corps carries out the first successful blood transfusion, using blood that had been stored and cooled. January 9 – WWI: Gallipoli Campaign: The last British troops are evacuated from Gallipoli, as the Ottoman Empire prevails over a joint British and French operation to capture Constantinople. January 10 – WWI: Erzurum Offensive: Russia defeats the Ottoman Empire.
1934January 1934 February 1934 January 1 – The International Telecommunication Union, a specialist agency of the League of Nations, is established. January 15 – The 8.0 Nepal–Bihar earthquake strikes Nepal and Bihar with a maximum Mercalli intensity of XI (Extreme), killing an estimated 6,000–10,700 people. January 26 – A 10-year German–Polish declaration of non-aggression is signed by Nazi Germany and the Second Polish Republic.
1921January 1921 January 2 The Association football club Cruzeiro Esporte Clube, from Belo Horizonte, is founded as the multi-sports club Palestra Italia by Italian expatriates in Brazil. The Spanish liner Santa Isabel breaks in two and sinks off Villa Garcia, Mexico, with the loss of 244 of the 300 people on board. January 16 – The Marxist Left in Slovakia and the Transcarpathian Ukraine holds its founding congress in Ľubochňa. January 17 – The first recorded public performance of the illusion of "sawing a woman in half" is given by English stage magician P.
1932January 1932 January 4 – The British authorities in India arrest and intern Mahatma Gandhi and Vallabhbhai Patel. January 9 – Sakuradamon Incident: Korean nationalist Lee Bong-chang fails in his effort to assassinate Emperor Hirohito of Japan. The Kuomintang's official newspaper runs an editorial expressing regret that the attempt failed, which is used by the Japanese as a pretext to attack Shanghai later in the month. January 22 – The 1932 Salvadoran peasant uprising begins; it is suppressed by the government of Maximiliano Hernández Martínez.
1933January 1933 January 11 – Sir Charles Kingsford Smith makes the first commercial flight between Australia and New Zealand. January 17 – The United States Congress votes in favour of Philippines independence, against the wishes of U.S. President Herbert Hoover. January 28 – "Pakistan Declaration": Choudhry Rahmat Ali publishes (in Cambridge, UK) a pamphlet entitled Now or Never; Are We to Live or Perish Forever?, in which he calls for the creation of a Muslim state in northwest India that he calls "Pakstan"; this influences the Pakistan Movement.
1915Below, the events of World War I have the "WWI" prefix. January 1915 January – British physicist Sir Joseph Larmor publishes his observations on "The Influence of Local Atmospheric Cooling on Astronomical Refraction". January 1 WWI: British Royal Navy battleship HMS Formidable is sunk off Lyme Regis, Dorset, England, by an Imperial German Navy U-boat, with the loss of 547 crew. Battle of Broken Hill: A train ambush near Broken Hill, Australia, is carried out by two men (claiming to be in support of the Ottoman Empire) who are killed, together with four civilians.
1928January 1928 January – British bacteriologist Frederick Griffith reports the results of Griffith's experiment, indirectly proving the existence of DNA. January 1 – Eastern Bloc emigration and defection: Boris Bazhanov, Joseph Stalin's personal secretary, crosses the border to Iran to defect from the Soviet Union. January 17 – The OGPU arrests Leon Trotsky in Moscow; he assumes a status of passive resistance and is exiled with his family. January 26 – The volcanic island Anak Krakatau appears.
1927January 1927 January 1 – The British Broadcasting Company becomes the British Broadcasting Corporation, when its Royal Charter of incorporation takes effect. John Reith becomes the first Director-General. January 7 The first transatlantic telephone call is made via radio from New York City, United States, to London, United Kingdom. The Harlem Globetrotters exhibition basketball team play their first ever road game in Hinckley, Illinois. January 9 – The Laurier Palace Theatre fire at a movie theatre in Montreal, Quebec, Canada, kills 78 children.
1922January 1922 January 7 – Dáil Éireann, the parliament of the Irish Republic, ratifies the Anglo-Irish Treaty by 64–57 votes. January 10 – Arthur Griffith is elected President of Dáil Éireann, the day after Éamon de Valera resigns. January 11 – The first successful insulin treatment of diabetes is made, by Frederick Banting in Toronto. January 15 – Michael Collins becomes Chairman of the Provisional Government of the Irish Free State. January 26 – Italian forces occupy Misrata, Libya; the reconquest of Libya begins.