1811

February 5: King George III relieved of duty because of insanity, George, Prince of Wales becomes the regent for the British Empire.

1811 (MDCCCXI) was a common year starting on Tuesday of the Gregorian calendar and a common year starting on Sunday of the Julian calendar, the 1811th year of the Common Era (CE) and Anno Domini (AD) designations, the 811th year of the 2nd millennium, the 11th year of the 19th century, and the 2nd year of the 1810s decade. As of the start of 1811, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.

Events

January–March

January 8 – An unsuccessful slave revolt is led by Charles Deslondes, in St. Charles and St. James Parishes, Louisiana.
January 17 – Mexican War of Independence – Battle of Calderón Bridge: A heavily outnumbered Spanish force of 6,000 troops defeats nearly 100,000 Mexican revolutionaries.
January 22 – The Casas Revolt begins in San Antonio, Spanish 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.
February 19 – Peninsular War – Battle of the Gebora: An outnumbered French force under Édouard Mortier routs and nearly destroys the Spanish, near Badajoz, Spain.
March 1 – Citadel Massacre in Cairo: Egyptian ruler Muhammad Ali kills the last Mamluk leaders.
March 5 – Peninsular War – Battle of Barrosa: A French attack fails, on a larger Anglo-Portuguese-Spanish force attempting to lift the Siege of Cádiz in Spain.
March 13 – Battle of Lissa: The British fleet defeats the French.
March 22 – The Commissioners' Plan 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.
March 28 – Henri Christophe is proclaimed King Henri I, turning the northern State of Haiti into the Kingdom of Haiti.

April–June

April 5–6 – Revolutionary riots occur in Buenos Aires.
May 14 – Paraguay declares independence from the Spanish Empire (recognised May 15).
May 16 – Peninsular War – Battle of Albuera: Spain, Portugal and Great Britain defeat the French.
May 18 – Battle of Las Piedras near Las Piedras, Banda Oriental: The independentists of Uruguay gain their first victory.
June 10 – A volcanic eruption briefly creates Sabrina Island (Azores).
June 15 – The Klågerup riots erupt in Sweden.
June 19 – The Carlton House Fête is held at the Prince Regent's London residence Carlton House to celebrate the establishment of the Regency era.

July–September

July 5 – Venezuela declares its Independence from the Spanish Empire.
July 9 – The Great Podil fire breaks out in Kiev, Ukraine.
July 9 – British explorer David Thompson posts a notice at the confluence of the Columbia and Snake Rivers (in modern-day Washington), claiming the area for the United Kingdom.
July 11 – The Russian Empire removes Anton II, Catholicos-Patriarch of All Georgia, from his office, placing a Russian-appointed bishop at the head of the Georgian church.
July 14
- Italian scientist Amedeo Avogadro publishes his memoir about the molecular content of gases.
- David Thompson reaches the mouth of the Columbia River, finding Fort Astoria under construction.
July 26 – Forest fires break out in the Tyrol region of Switzerland, reportedly destroying 64 villages and hamlets.
July 30 – Mexican War of Independence: Priest and military leader Miguel Hidalgo y Costilla is executed as a rebel, by the Spanish government of New Spain.
August 3 – Jungfrau, the third highest summit in the Bernese Alps, is first ascended.
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 City and Hoboken, New Jersey.
October 17 – The silver deposits of Agua Amarga in Chile are discovered becoming, in the following years, instrumental for the Patriots to finance the Chilean War of Independence.
October 23 – José Gervasio Artigas and 16,000 orientales leave the Banda Oriental del Uruguay, to go into exile.
October 26 – The Argentine Government declares freedom of expression for the press.
November 4 – Luddite uprisings, in which workers destroy industrial machines, begin in northern England and the Midlands. According to one historian, "The first attack on textile machines by men who used the name 'General Ludd' and called themselves his followers, was on the night of 4th November 1811 in the village of Bulwell, four miles north of Nottingham, when a small band of men gathered in the darkness and marched to the home of a master weaver called Hollingsworth," then destroyed six of his weaving machines.
November 7 – Battle of Tippecanoe: American troops led by William Henry Harrison defeat the Native American spiritual leader Tenskwatawa, also known as The Prophet (Chief Tecumseh's brother).
November 17 – José Miguel Carrera, Chilean founding father, is sworn in as President of the executive Junta of the government of Chile.
December 2 – Reverend Samuel Marsden sends the first commercial shipment of wool from New South Wales to England.
December 16 – The New Madrid earthquake in the 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.
December 21 – The first Constitution of the Republic of Venezuela, after it declares its independence from Spain, goes into effect.
December 26 – The Richmond Theatre fire in Virginia kills 72 people, including the Governor of Virginia George William Smith and the president of the First National Bank of Virginia, Abraham B. Venable.