Editing 1866 (section)

== Deaths ==

=== January–June ===
* January (date unknown) – [[Thomas Baldwin Marsh]], American religious leader (b. [[1799]])
* [[January 16]] – [[Phineas Quimby]], American physician (b. [[1802]])
* [[January 19]] – [[Harriet Ludlow Clarke]], British artist
* [[January 23]] – [[Thomas Love Peacock]], English satirist (b. [[1785]])
* [[January 31]] – [[Friedrich Rückert]], German poet, translator and professor of Oriental languages (b. [[1788]])
* [[February 25]] – [[Sarah Ann Gill]], Barbadian national heroine (b. [[1795]])
* [[March 4]] – [[Alexander Campbell (clergyman)|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 24]] – [[Maria Amalia of Naples and Sicily]], Queen of France (b. [[1782]])<ref>{{cite web |title=Marie-Amélie de Bourbon {{!}} queen of France {{!}} Britannica |url=https://www.britannica.com/biography/Marie-Amelie-de-Bourbon |website=www.britannica.com |access-date=6 September 2022 |language=en}}</ref>
* [[March 28]] – [[Solomon Foot]], American politician (b. [[1802]])
* [[March 29]] – [[John Keble]], British churchman (b. [[1792]])
* [[April 1]] – [[Elizabeth Jesser Reid]], English social reformer, founder of [[Bedford College (London)|Bedford College]] (b. [[1789]])
* [[April 4]]  – [[William Dick (veterinarian)|William Dick]], founder of [[Royal (Dick) School of Veterinary Studies|Edinburgh Veterinary College]] (b. [[1793]])
* [[April 5]] – [[Thomas Hodgkin]], British physician (b. [[1798]])
* [[April 7]] – [[Johann Sedlatzek]], German flautist (b. [[1789]])
* [[April 12]] – [[Peter Hesketh-Fleetwood]], English Member of Parliament and developer (b. [[1801]])
* [[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 for whom [[Seattle]] is named (b. c. [[1786]])
* [[June 17]] – [[Lewis Cass]], American military officer, politician, and statesman (b. [[1782]])

=== July–December ===
[[File:Georg Friedrich Bernhard Riemann.jpeg|thumb|right|110px|[[Bernhard Riemann]]]]
* [[July 20]] – [[Bernhard Riemann]], German mathematician (b. [[1826]])
* [[July 25]] – [[Floride Calhoun]], Second Lady of the United States (b. 1792)
* [[July 29]] – [[Madame Clicquot Ponsardin]], French champagne producer  (b. [[1777]]) 
* [[August 1]] – John Ross, long-serving principal chief of the [[Cherokee Nation]], of natural causes, in Washington D. C. (born 1790 in Cherokee Nation East).
* [[August 6]] – [[Christian Eric Fahlcrantz]], Swedish writer (b. [[1790]])
* [[August 20]] – [[Maria De Mattias]], Italian Catholic saint (b. [[1805]])
* [[August 29]] – [[Tokugawa Iemochi]], 14th ''[[shōgun]]'' of the [[Tokugawa shogunate]] of Japan (b. [[1846]])
* [[September 4]] – [[Theresa Pulszky]], European author (b. [[1819]])
* [[September 30]] – [[Per Gustaf Svinhufvud af Qvalstad]], Swedo-Finnish treasurer of [[Tavastia (historical province)|Tavastia province]], manor host, and paternal grandfather of President [[P. E. Svinhufvud]] (b. 1804)<ref>[https://suomenpresidentit.fi/svinhufvud/?lang=en PEHR EVIND SVINHUFVUD (1861–1944), 1ST REGENT OF FINLAND (1918), 3RD PRESIDENT OF FINLAND (1931–1937)]</ref>
* [[October 13]] – [[Celadon Leeds Daboll]], American merchant and inventor (b. [[1818]])
* [[October 18]] – [[Manuel Bulnes]], Chilean general and politician, [[President of Chile]] (b. [[1799]])
* [[November 11]] – [[Agustín Jerónimo de Iturbide y Huarte]], Prince Imperial of Mexico (b. [[1807]])
* [[November 14]] – King [[Miguel I of Portugal]] (b. [[1802]])
* [[November 26]] – [[Jean-Jacques Willmar]], Luxembourg politician (b. [[1792]])
* [[December 1]] – [[George Everest]], Welsh geodesist (b. [[1790]])
* [[December 21]] – [[William J. Fetterman]], United States Army officer (b. [[1835]]?)<ref>{{cite journal |url=https://archive.org/details/annalsofwyom63141991wyom/page/42 |title=Price of Arrogance: The Short and Controversial Life of William Judd Fetterman |last=McDermott |first=John D. |journal=Annals of Wyoming by Wyoming State Historical Society |volume=63 |issue=2 |pages=42–53 |date=Spring 1991}}</ref>
* December 21 – [[Mercedes Marín del Solar]], Chilean poet, reform educator (b. [[1804]])
* [[December 25]] – [[Hayrullah Efendi]], Ottoman physician, historian, and official (b. [[1818]])<ref>{{TDV Encyclopedia of Islam|volume=17 |pages=67–75 |last=Akün |first=Ömer Faruk |title=Hayrullah Efendi |url=https://islamansiklopedisi.org.tr/hayrullah-efendi}}</ref>

===Date unknown===
*[[Du Bois Agett]], early settler of Western Australia (b. [[1796]])