1887January 11 – Louis Pasteur's anti-rabies treatment is defended in the Académie Nationale de Médecine, by Dr. Joseph Grancher. January 20 The United States Senate allows the Navy to lease Pearl Harbor as a naval base. British emigrant ship Kapunda sinks after a collision off the coast of Brazil, killing 303 with only 16 survivors. January 21 The Amateur Athletic Union (AAU) is formed in the United States. Brisbane receives a one-day rainfall of (a record for any Australian capital city).
1898January 1 – New York City annexes land from surrounding counties, creating the City of Greater New York as the world's second largest. The city is geographically divided into five boroughs: Manhattan, Brooklyn, Queens, The Bronx and Staten Island. January 13 – Novelist Émile Zola's open letter to the President of the French Republic on the Dreyfus affair, J'Accuse...!, is published on the front page of the Paris daily newspaper L'Aurore, accusing the government of wrongfully imprisoning Alfred Dreyfus and of antisemitism.
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.
1973January 1973 January 1 – The United Kingdom, the Republic of Ireland and Denmark enter the European Economic Community, which later becomes the European Union. January 15 – Vietnam War: Citing progress in peace negotiations, U.S. President Richard Nixon announces the suspension of offensive action in North Vietnam. January 17 – Ferdinand Marcos becomes President for Life of the Philippines. January 20 – Richard Nixon is sworn in for a second term as President of the United States.
1886January 1 – Upper Burma is formally annexed to British Burma, following its conquest in the Third Anglo-Burmese War of November 1885. January 5–9 – Robert Louis Stevenson's novella Strange Case of Dr Jekyll and Mr Hyde is published in New York and London. January 16 – A resolution is passed in the German Parliament to condemn the Prussian deportations, the politically motivated mass expulsion of ethnic Poles and Jews from Prussia, initiated by Otto von Bismarck.
1881January 1–24 – Siege of Geok Tepe: Russian troops under General Mikhail Skobelev defeat the Turkomans. January 13 – War of the Pacific – Battle of San Juan and Chorrillos: The Chilean army defeats Peruvian forces. January 15 – War of the Pacific – Battle of Miraflores: The Chileans take Lima, capital of Peru, after defeating its second line of defense in Miraflores.