2nd January » Amadeo I of Spain e.g Amadeus I becomes Monarchy of Spain or King of Spain.
19th January » Franco-Prussian War: In the Siege of Paris (1870-1871) Siege of Paris, Kingdom of Prussia Prussia wins the Battle of St. Quentin (1871) Battle of St. Quentin. Meanwhile, the French attempt to break the siege in the Battle of Buzenval (1871) Battle of Buze
28th January » Franco-Prussian War: the Siege of Paris (1870–71) e.g Siege of Paris ends in French defeat and an armistice.
17th February » The victorious Prussian Army parades through Paris, France after the end of the Siege of Paris (1870-1871) named Siege of Paris during the Franco-Prussian War.
18th March » Declaration of the Paris Commune; President of the French Republic, Adolphe Thiers, orders the evacuation of Paris.
21st March » Otto von Bismarck is appointed Chancellor of the German Empire.
21st March » Journalist Henry Morton Stanley begins his trek to find the missionary and explorer David Livingstone.
22nd March » In North Carolina, William Woods Holden becomes the first Governor (United States) e.g governor of a U.S. state to be removed from office by impeachment.
27th March » The 1871 England versus Scotland rugby union match first international rugby football match, when Scotland national rugby union team Scotland defeats England national rugby union team England in Edinburgh at Raeburn Place.
28th March » The Paris Commune is formally established in Paris.
29th March » The Royal Albert Hall is opened by Queen Victoria.
1st April » The first stage of the Brill Tramway opens.
20th April » The Civil Rights Act of 1871 becomes law.
30th April » The Camp Grant massacre takes place in Arizona Territory.
4th May » The National Association of Professional Base Ball Players called National Association, the first professional baseball league, opens its first season in Fort Wayne, Indiana.
21st May » French troops invade the Paris Commune and engage its residents in street fighting. By the close of "Bloody Week", some 20,000 communards have been killed and 38,000 arrested.
21st May » Opening of the first rack railway in Europe, the Rigi-Bahnen on Mount Rigi.
22nd May » The United States Army known as U.S. Army issues an order for abandonment of Fort Kearny in Nebraska.
10th June » Sinmiyangyo: Captain McLane Tilton leads 109 United States Marine Corps e.g US Marines in a naval attack on Han River (Korea) known as Han River forts on Kanghwa Island, Korea.
16th June » The Test Act University Tests Act allows students to enter the Universities of University of Oxford Oxford, University of Cambridge Cambridge and University of Durham Durham without religious tests (except for those intending to study theology).
2nd July » Victor Emmanuel II of Italy enters Rome after having conquered it from the Papal States.
20th July » British Columbia joins the confederation of Canada.
29th August » Emperor Meiji orders the abolition of the han system and the establishment of Prefectures of Japan called prefectures as local centers of administration. (Traditional Japanese calendar known as Japanese date: July 14, 1871).
20th September » Bishop John Coleridge Patteson is martyred on the island of Nukapu, a Polynesian outlier island now in the Temotu Province of the Solomon Islands. He is the first bishop of Melanesia.
28th September » Brazilian Parliament passes the Law of the Free Womb, granting freedom to all new children born to slaves, the first major step in the eradication of slavery in Brazil.
8th October » Four major fires break out on the shores of Lake Michigan in Chicago, Peshtigo, Wisconsin, Holland, Michigan, and Manistee, Michigan including the Great Chicago Fire, and the much deadlier Peshtigo Fire.
10th October » The Great Chicago Fire: Chicago burns after a barn accident. The fire lasts from October 8 to October 10.
10th November » Henry Morton Stanley locates missing explorer and missionary, Dr. David Livingstone in Ujiji, near Lake Tanganyika, famously greeting him with the words, "Dr. Livingstone, I presume?".
17th November » The National Rifle Association is granted a charter by the state of New York.
26th December » Gilbert and Sullivan collaborate for the first time, on their lost opera, 'Thespis (opera) named Thespis'. It does modestly well, but the two would not collaborate again for four years.