Events of 1811

January - March

• January 3 - An unsuccessful slave revolt is led by Charles Deslandes in St. Charles and St. James, Louisiana.
• January 22 - The " Casas Revolt" begins in San Antonio, Texas.
• February 5 - British Regency: George, Prince of Wales becomes Prince Regent because of the perceived insanity of his father, King George III of the United Kingdom.
• March 1 - Citadel Massacre: Egyptian ruler Mohammed Ali kills the last Mamluk leaders.
• March 13 - Battle of Lissa (1811): The British fleet defeats the French.
• March 22 - The Commissioners' Plan of 1811 for Manhattan is presented.
• March 25 - The Great Comet of 1811 is discovered by Honoré Flaugergues.
• March 27 - Battle of Anholt: The British navy defeats Denmark.

April - June

• April 5- April 6 - Revolutionary riots occur in Buenos Aires.
• May 14 - Paraguay declares independence from Spain.
• May 16 - Battle of Albuera: Spain, Portugal and Great Britain defeat the French.
• June 9 - The Great fire of the Podil breaks out in Kiev, Ukraine.

July - September

• July 5 - Venezuela declares its independence from Spain.
• July 11 - Italian scientist Amedeo Avogadro publishes his memoire about the molecular content of gases.
• September - Nathan of Breslov leads the first annual Rosh Hashana kibbutz (pilgrimage) of Breslov Hasidim to the grave of Rabbi Nachman of Breslov in Uman, Ukraine.

October - December

• October 11 - Inventor John Stevens' boat, the Juliana, begins operation as the first steam-powered ferry (service between New York, New York, and Hoboken, New Jersey).
• November - Luddite uprisings begin in northern England and the Midlands.
• November 6 - Battle of Tippecanoe: American troops led by William Henry Harrison defeat the Native American chief Tecumseh.
• December 16 - The New Madrid earthquake in Mississippi Valley near New Madrid reverses the course of the river for a while. Other earthquakes along the fault occur on January 23, 1812 and February 7, 1812.

Ongoing events

• Argentine War of Independence (1810-1818)
• Black War (1804-1835)
• Bolivian Independence War (1809-1824)
• Gunboat War (1807-1814)
• Mtetwa Empire Expansion
• Napoleonic Wars (1799-1815) - Peninsular War
• Russo-Persian War (1804-1813)
• Russo-Turkish War, 1806-1812

Births

January - June

• January 9 - Gilbert Abbott à Beckett, English writer (d. 1856)
• January 17 - Joshua Abraham Norton, self-declared Emperor Norton I of the United States (d. 1880)
• February 3 - Horace Greeley, American journalist, editor, and publisher (d. 1872)
• February 6 - Henry George Liddell, English clergyman (d. 1898)
• March 20 - Napoleon II of France (d. 1832)
• March 21 - Nathaniel Woodard, English eeducationalist (d. 1891)
• March 30 - Robert Bunsen, German chemist and inventor (d. 1899)
• May 11
• Chang and Eng Bunker, Siamese twins and sideshow performers
• Jean-Jacques Challet-Venel, member of the Swiss Federal Council (d. 1893)
• June 14 - Harriet Beecher Stowe, American author (d. 1896)

July - December

• July 18 - William Makepeace Thackeray, British novelist (d. 1863)
• August 31 - Theophile Gautier, French writer (d. 1872)
• September 19 - Orson Pratt, American religious leader (d. 1881)
• October 22 - Franz Liszt, Hungarian composer and pianist (d. 1886)
• October 25 - Évariste Galois, French mathematician (d. 1832)
• October 27 - Stevens Thomson Mason, first governor of Michigan (d. 1843)
• November 21
• Zeng Guofan, Chinese official and military leader (d. 1872)
• Ludwig Preiss, Botanical collector (d. 1883)
• November 24 - Ulrich Ochsenbein, Swiss Federal Councilor (d. 1890)
• December 21 - Archibald Campbell Tait, Archbishop of Canterbury (d. 1882)
• date unknown
• Mohammad Afzal Khan, Emir of Kabul, Emir of Kandahar (d. 1867)

Deaths

January - June

• January 10 - Marie-Joseph Chénier, French poet (b. 1764)
• February 26 - Mateo de Toro Zambrano y Ureta, Governor of Chile (b. 1727)
• March 14 - Augustus FitzRoy, 3rd Duke of Grafton, Prime Minister of the United Kingdom (b. 1735)
• April 7 - Garsevan Chavchavadze, Georgian diplomat and politician (b. 1757)
• May 4 - Nikolay Kamensky, Russian general (b. 1776)
• May 28 - Henry Dundas, 1st Viscount Melville, British minister (b. 1742)
• June 26 - Ignacio Allende, captain of the Spanish Army in Mexico

July - December

• July 30 - Miguel Hidalgo y Costilla, Mexican revolutionary (b. 1753)
• August - William Williams, signer of the Declaration of Independence (b. 1731)
• August 20 - Louis Antoine de Bougainville, French navigator and military commander (b. 1729)
• September - Ulrich Jasper Seetzen, explorer (b. 1767)
• September 8 - Peter Simon Pallas, German zoologist (b. 1741)
• October 11 - Johann Conrad Ammann, Swiss physician and naturalist (b. 1724)
• November 18 - Adam Weishaupt, German founder of the Illuminati (b. 1748)
• November 21 - Heinrich von Kleist, German writer (suicide) (b. 1777)
• November 27 - Andrew Meikle, English engineer (b. 1719)