Events

January–March

• January 1 – The last issue of the abolitionist magazine The Liberator is published.

• January 6 – Ottoman troops clash with men of a Maronite leader Karam in St. Doumit in Lebanon; the Ottomans are defeated.

• January 12 – The Royal Aeronautical Society is formed (London).

• February 7 – Battle of Abtao: A Spanish naval squadron fights a combined Peruvian-Chilean fleet, at the island of Abtao in the Chiloé Archipelago of central Chile.

• February 13 – The first daylight bank robbery in United States history during peacetime takes place in Liberty, Missouri. This is considered to be the first robbery committed by Jesse James and his gang, although James's role is disputed.

• February 26 – The Calaveras Skull is discovered. Purported to be evidence of humans during the Pliocene Age, it turns out to be a hoax.

• February 28 – The month concludes without having a full moon.

April–June

• April 4 – Alexander II of Russia narrowly escapes an assassination attempt in the city of Kiev.

• April 10 – The American Society for the Prevention of Cruelty to Animals (ASPCA) is founded in New York City by Henry Bergh.

• May – Student Ferdinand Cohen-Blind fails to assassinate Otto von Bismarck in Unter den Linden in Berlin.

• May 2 – Battle of Callao: Peruvian defenders fight the Spanish fleet.

May 16: U.S. nickel coin approved.

• May 11 – London bank Overend, Gurney and Company collapses, precipitating a financial crisis.

• May 16 – The U.S. Congress approves the minting of a nickel 5-cent coin (nickel), eliminating its predecessor, the half dime.

• May 24 – Battle of Tuyutí: 32,000 soldiers of the Triple Alliance defeat 24,000 Paraguayan soldiers few miles north of the Paraná, Argentina, with 16,000 casualties.

• May 26 – First Production of Cox and Box by Francis Burnand and Arthur Sullivan at Moray Lodge, Kensington

• June 2 – Fenian forces skirmish with Canadian militia at Ridgeway and Fort Erie.

• June 5 – Calculations indicate Pluto reaches its most recent aphelion (furthest point from Sun) on this day (the next aphelion will occur in August 2113).

• June 8 – The Canadian Parliament meets for the first time in Ottawa.

• June 11 – The Agra High Court is established (later shifted to the Allahabad High Court).

• June 14 – The Austro-Prussian War begins, when the Austrians and most of the medium German states declare war on Prussia.

• June 20 – The Kingdom of Italy declares war on Austria.

• June 27–June 29 – Battle of Langensalza: The Prussians defeat the Hanoverian army.

July–September

• July 1 – The first Constitution of Romania is issued.

• July 3 – Battle of Königgratz: the Prussian army under King Wilhelm and Helmuth von Moltke defeats the Austrian army of Lajos Benedek, leading to a decisive Prussian victory in the Austro-Prussian War.

• July 5 – Princess Helena of the United Kingdom, third daughter of Queen Victoria, maries Prince Christian of Schleswig-Holstein-Sonderburg-Augustenburg.

• July 20 – Naval Battle of Lissa: The Austrian fleet under Wilhelm von Tegetthoff defeats the Italian fleet of Carlo di Persano.

• July 24 – Reconstruction: Tennessee becomes the first U.S. state to be readmitted to the Union following the American Civil War.

• July 25 – The U.S. Congress passes legislation authorizing the rank of General of the Army (now called "5-star general"); Lieutenant General Ulysses S. Grant becomes the first to have this rank.

July 27: Atlantic Cable.

• July 27 – The Atlantic Cable is successfully completed, allowing transatlantic telegraph communication for the first time.

• July 28 – The Metric Act of 1866 becomes law and legalizes the standardization of weights and measures in the United States.

• August 23 – The Treaty of Prague ends the Austro-Prussian War.

• September – The Great Tea Race of 1866 ends in London, narrowly won by the clipper ship Taeping.

• September 22 – Paraguay successfully defends Curupaity against the Triple Alliance, killing more than 5,000 with just about 50 casualties.

October–December

Alfred Nobel.

• October 12 – The Treaty of Vienna ends the war between Austria and Italy; it formalizes the annexation of Venetia by Italy.

• October 14 – French troops under the command of Rear Admiral Pierre-Gustave Roze land at Ganghwa Island, Korea as part of a punitive expedition against that kingdom for the execution of French Jesuit priests. It is the first military contact between Korea and a Western force.

• November 7 – The Ruse-Varna railway line (the first railway in Bulgaria) officially opens.

Undated

• Federalist revolts occur in Argentina.

• In Sweden, the Riksdag of the Estates is replaced by an elected 2-chamber assembly, the Riksdag.

• Alfred Nobel invents dynamite in Germany.

• Cereal partners Nestle and General Mills are founded

Ongoing

• Caste War of Yucatán (1847–1901)

• French intervention in Mexico (1862–1867)

• New Zealand land wars (1843–1872)

• Snake War (1864–1868)

• War of the Triple Alliance (1864–1870)

Births

January–June

• January 13 – Vasily Kalinnikov, Russian composer (d. 1901)

• January 15 – Nathan Söderblom, Swedish archbishop, recipient of the Nobel Peace Prize (d. 1931)

• January 29 – Romain Rolland, French writer, Nobel Prize laureate (d. 1944)

• February 9 – George Ade, American writer, newspaper columnist, and playwright (d. 1944)

• March 5 – Arthur Leopold Busch, American Submarine pioneer (d. 1956)

• March 30 – George Van Haltren, baseball player (d. 1945)

• April 1 – Ferruccio Busoni, Italian pianist and composer (d. 1924)

• April 13 – Butch Cassidy, American outlaw (d. 1909)

• April 14 – Anne Sullivan, tutor of Helen Keller (d. 1936)

• April 17 – Ernest Starling, British physiologist (d. 1927)

• April 24 – Ishii Kikujiro, Japanese diplomat (d. 1945)

• May 5 – Thomas B. Thrige, Danish industrialist (d. 1938)

• May 17 – Erik Satie, French composer (d. 1925)

• May 22 – Charles F. Haanel, American New Thought author and businessman (d. 1949)

• June 4 – Miina Sillanpää, Finnish politician (d. 1952)

• June 26 – George Herbert, 5th Earl of Carnarvon, English financier of Egyptian excavations (d. 1923)

July–December

• July 3 – Albert Gottschalk, Danish painter (d. 1906)

• July 6 – Charles Mangin, French general (d. 1925)

• July 13 – La Goulue, French dancer (d. 1929)

• July 28 – Beatrix Potter, English children's author (d. 1943)

• August 6 – Matthew Henson, American explorer (d. 1955)

• August 12 – Jacinto Benavente, Spanish writer, Nobel Prize laureate (d. 1954)

• August 17 – Julia Marlowe, stage actress (d. 1950)

• September 1 – James J. Corbett, American boxer (d. 1933)

• September 7 – Tristan Bernard, French writer (d. 1947)

• September 10 – Jeppe Aakjaer, Danish poet and novelist (d. 1930)

• September 21

• *Charles Nicolle, French bacteriologist, recipient of the Nobel Prize in Physiology or Medicine (d. 1936)

• *H. G. Wells, English writer (d. 1946)

• September 27 – Eurosia Fabris, Italian Catholic Blessed (d. 1932)

• September 25 – Thomas Hunt Morgan, American geneticist, recipient of the Nobel Prize in Physiology or Medicine (d. 1945)

• October 12 – Ramsay MacDonald, Prime Minister of the United Kingdom (d. 1937)

• November 12 – Sun Yat-sen, Chinese revolutionary (d. 1925)

• December 4th Wassily Kandinsky born in moscow

• November 28 – David Warfield, stage actor (d. 1951)

• November 30 – Robert Broom, Scottish paleontologist (d. 1951)

• December 12 – Alfred Werner, German chemist, Nobel Prize laureate (d. 1919)

• December 16 (December 4 O.S.) – Wassily Kandinsky, Russian-born painter (d. 1944)

Deaths

January–June

• January 23 – Thomas Love Peacock, English satirist (b. 1785)

• January 31 – Friedrich Rückert, German poet, translator, and professor of Oriental languages (b. 1788)

• January – Thomas Baldwin Marsh, American religious leader (b. 1799)

• March 4 – Alexander Campbell, Irish/U.S. founder of the Disciples of Christ (b. 1788)

• March 6 – William Whewell, English scientist, philosopher, and historian of science (b. 1794)

• March 20 – Rikard Nordraak, Norwegian composer (b. 1842)

• March 21 – Nadezhda Durova, first female Russian military officer (b. 1783)

• March 28 – Solomon Foot, American politician (b. 1802)

• April 4 – William Dick, founder of Edinburgh Veterinary College (b. 1793)

• April 5 – Thomas Hodgkin, British physician (b. 1798)

• May 13 – Nikolai Brashman, Russian mathematician of Czech origin (b.1796)

• May 29 – Winfield Scott, American general and presidential candidate (b. 1786)

• June 7 – Chief Sealth, Native American whom Seattle is named for (b. c. 1786)

July–December

• July 20 – Bernhard Riemann, German mathematician (b. 1826)

• July 25 – Floride Calhoun, Second Lady of the United States (b. 1792)

• August 6 – Christian Eric Fahlcrantz, Swedish writer (b. 1790)

• August 20 – Maria De Mattias, Catholic saint (b. 1805)

• August 29 – Tokugawa Iemochi, 14th shogun of the Tokugawa Shogunate of Japan (b. 1846)

• October 13 – Celadon Leeds Daboll, American merchant and inventor (b. 1818)

• November 11 – Agustin Jerónimo de Iturbide y Huarte, Prince Imperial of Mexico (b. 1807)

• November 26 – Jean-Jacques Willmar, Luxembourg politician (b. 1792)

• December 1 – George Everest, Welsh geodesist (b. 1790)