|Centuries:||18th century – 19th century – 20th century|
|Decades:||1780s 1790s 1800s – 1810s – 1820s 1830s 1840s|
|Years:||1809 1810 1811 – 1812 – 1813 1814 1815|
|1812 in topic:|
|Archaeology – Architecture – Art – Literature – Music|
|Australia – Brazil - Canada – Denmark - France – Germany – Mexico – Norway - Philippines - Portugal– Russia - South Africa – Spain - Sweden - United Kingdom – United States|
|Rail Transport – Science – Sports|
|Lists of leaders|
|Colonial Governors – State leaders|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Ab urbe condita||2565|
|British Regnal year||52 Geo. 3 – 53 Geo. 3|
|Chinese calendar||辛未年 (Metal Goat)
4508 or 4448
— to —
壬申年 (Water Monkey)
4509 or 4449
|- Vikram Samvat||1868–1869|
|- Shaka Samvat||1734–1735|
|- Kali Yuga||4913–4914|
|Japanese calendar||Bunka 9
|Julian calendar||Gregorian minus 12 days|
|Minguo calendar||100 before ROC
|Thai solar calendar||2354–2355|
|Wikimedia Commons has media related to 1812.|
1812 (MDCCCXII) was a leap year starting on Wednesday (dominical letter ED) of the Gregorian calendar and a leap year starting on Monday (dominical letter GF) of the Julian calendar, the 1812th year of the Common Era (CE) and Anno Domini (AD) designations, the 812th year of the 2nd millennium, the 12th year of the 19th century, and the 3rd year of the 1810s decade. Note that the Julian day for 1812 is 12 calendar days difference, which continued to be used from 1582 until the complete conversion of the Gregorian calendar was entirely done in 1929.
- January 1 – The Allgemeines bürgerliches Gesetzbuch (the Austrian civil code) enters into force in the Austrian Empire.
- February 7
- February 12 – Napoleon authorizes the usage of Mesures usuelles, the basis of the metric system.
- February 13 – First Chilean newspaper Aurora de Chile is dealing with political philosophy and standing in favor of the new national government.
- February 27 – English poet Lord Byron gives his first address as a member of the House of Lords, in defense of Luddite violence against industrialism in his home county of Nottinghamshire.
- February 27 – Argentine War of Independence: Manuel Belgrano raises the Flag of Argentina in the city of Rosario for the first time.
- March 5 – Prussia and France sign the Treaty of Paris
- March 15 – Luddites attack the wool-processing factory of Frank Vickerman in West Yorkshire.
- March 19 – The Cádiz Cortes, in exile, create the first modern Spanish constitution.
- March 16–April 6 – Siege of Badajoz (Peninsular War): The Anglo-Portuguese Army, under the Earl of Wellington, besieges Badajoz in Spain and forces surrender of the French garrison.
- March 26
- In the United States, the Boston Gazette prints a political cartoon coining the term "Gerrymander" after former Massachusetts Governor Elbridge Gerry's approval (on February 11) of legislation creating oddly shaped electoral districts designed to help incumbents win re-election.
- The 1812 Caracas earthquake destroys Caracas in Venezuela.
- April 4 – U.S. President James Madison enacts a 90-day embargo on trade with the United Kingdom.
- April 30 – Louisiana is admitted as the 18th U.S. state.
- May 11 – John Bellingham assassinates British Prime Minister Spencer Perceval in the lobby of the British House of Commons.
- May 16 – Russian Field Marshal Mikhail Kutuzov signs the Treaty of Bucharest, ending the Russo-Turkish War (1806–12) and annexing Bessarabia to Imperial Russia.
- May 25 – Felling mine disaster: A mine explosion at the Felling colliery near Jarrow, England leaves 96 dead.
- June 1 – War of 1812: U.S. President James Madison asks the U.S. Congress to declare war on the United Kingdom.
- June 4 – Following Louisiana's admittance as a U.S. state, the territory by that name is renamed the Missouri Territory.
- June 16 – New York State charters City Bank of New York, which later became Citibank.
- June 18 – The War of 1812 between the United States, Canada and the United Kingdom begins.
- June 24 – Napoleon's Grande Armée crosses the Neman River and invades Russia.
- July 12 – Americans invade Canada at Windsor, Ontario.
- July 18 – Russia's Patriotic War – Battle of Klyastitsy: Kulnev defeats Oudinot but sustains a mortal wound.
- July 22 – Peninsular War – Battle of Salamanca: British forces led by Lord Wellington defeat French troops near Salamanca in Spain.
- August 5 – War of 1812: Tecumseh's Indian force ambushes Thomas Van Horne's 200 Americans at Brownstone Creek, causing them to flee and retreat.
- August 12 – Peninsular War: The combined English and Portuguese army under the command of Wellington enters Madrid following the Battle of Salamanca.
- August 15 – War of 1812: Battle of Fort Dearborn – Potawatomi warriors overrun the United States fort in [Illinois Territory].
- August 16 – War of 1812: American General William Hull surrenders Fort Detroit without a fight to the British Army.
- August 19 – War of 1812: The USS Constitution defeats the British frigate Guerriere off the coast of Nova Scotia. The British shot is said to have bounced off the Constitution's sides, earning her the nickname "Old Ironsides".
- September 7 – Napoleonic Wars – French invasion of Russia – Battle of Borodino: The bloodiest battle of the Napoleonic Wars ends in a tactical victory for Napoleon. There are at least 70,000 casualties, with a minimum of 6,562 dead from the French Grande Armée alone.
- September 14 – French invasion of Russia: Napoleon's troops enter Moscow, which is deliberately set on fire by Muscovites on orders of Fyodor Rostopchin.
- October – The capital of the Commonwealth of Pennsylvania, United States is permanently moved from Lancaster to Harrisburg.
- October 9 – War of 1812: American naval forces under Lieutenant Jesse Duncan Elliott capture two British warships, HMS Detroit and HMS Caledonia.
- October 13 – War of 1812 – Battle of Queenston Heights: As part of the Niagara campaign in Ontario, Canada, United States forces under General Stephen Van Rensselaer are repulsed from invading Canada by British and native troops led by Sir Isaac Brock (who dies during the battle).
- October 18–20 – Second Battle of Polotsk – Russians attack and defeat a Franco-Bavarian force in Belarus.
- October 19 – Napoleon begins his retreat from Moscow.
- October 23 – Malet coup of 1812: General Claude François de Malet attempts unsuccessfully to overthrow the Napoleonic régime in Paris.
- October 24 – Napoleonic Wars – Battle of Maloyaroslavets: An inconclusive encounter between the French vanguard and a Russian force leads Napoleon to decide to retreat along the same line as his advance, with disastrous results.
- November 3 – Napoleonic Wars – Battle of Vyazma: The rearguard of Napoleon's retreating army is defeated.
- November 5 – James Madison defeats DeWitt Clinton in the U.S. presidential election.
- November 10 – A general election in the United Kingdom sees victory for the Tory Party under Robert Jenkinson, 2nd Earl of Liverpool.
- November 15–18 – Napoleonic Wars – Battle of Krasnoi: Napoleon's retreating army is again defeated in a series of skirmishes.
- December 8 – The 1812 Wrightwood earthquake affects Southern California.
- December 20 – The first volume of Grimms' Fairy Tales is published in Germany.
- December 29 – War of 1812: The USS Constitution defeats the British frigate HMS Java off the coast of Brazil.
- December 30 – Convention of Tauroggen is signed.
- The Bishop James Madison Society is founded at the College of William & Mary, Williamsburg, Virginia.
- The Woodford Reserve Bourbon whiskey distillery, established in 1780 along Glenn's Creek in Woodford County, Kentucky, passes to the control of Oscar Pepper.
- The capital of Finland is moved from Turku to Helsinki.
- Approximate date – Battle of Shela: People of Lamu Island are victorious against those from other parts of the Kenya coast.
- January 6 – Melchora Aquino, Filipino revolutionary hero (d. 1919)
- January 13 – Victor de Laprade, French poet and critic (d. 1883)
- February 3 – William Fraser Tolmie, Scottish-Canadian scientist and politician (d. 1886)
- February 7 – Charles Dickens, English writer (d. 1870)
- February 11 – Alexander Hamilton Stephens, Vice President of the Confederate States of America (d. 1883)
- February 15 – Charles Lewis Tiffany, American jeweler, and co-founder of Tiffany & Co. (d. 1902)
- February 29 – Sir James Milne Wilson, Premier of Tasmania (d. 1880)
- March 1 – Augustus Pugin, English-born architect (d. 1852)
- March 6 – Aaron Lufkin Dennison, American watch manufacturer (d. 1895)
- March 22 – Stephen Pearl Andrews, American anarchist and abolitionist (d. 1886)
- April 22 – Solomon Caesar Malan, Swiss-born orientalist (d. 1894)
- April 27
- April 29 – Emilie Högquist, Swedish dramatic star (d. 1846)
- May 7 – Robert Browning, English poet (d. 1889)
- May 12 – Edward Lear, English artist and poet (d. 1888)
- June 9 – Johann Gottfried Galle, German astronomer (d. 1910)
- June 13 – Gustavus H. Scott, American admiral (d. 1882)
- June 14 – Fernando Wood, New York City mayor (d. 1881)
- July 2 – Nathaniel de Rothschild, French wine grower (d. 1870)
- August 8 – John Rodgers, American admiral (d. 1882)
- August 25 – Percival Drayton, United States Navy officer (d. 1865)
- November 14 – Aleardo Aleardi, Italian poet (d. 1878)
- December 14 – Charles Canning, 1st Earl Canning, British Viceroy of India (d. 1862)
- December 17 – Vilhelm Petersen, Danish painter (d. 1880)
- December 24 – Karl Eduard Zachariae von Lingenthal, German jurist (d. 1894)
- Louis du Couret, French explorer, military officer, and writer (d. 1867)
- Mohan Lal (Zutshi), Indian traveler (d. 1877)
- January 23 – Robert Craufurd, British general (mortally wounded in battle) (b. 1764)
- March 7 – Isaac Swainson, English botanist (b. 1746)
- March 11 – Philip James de Loutherbourg, English artist (b. 1740)
- April 20 – George Clinton, 4th Vice President of the United States (b. 1739)
- April 25 – Edmond Malone, Irish scholar (b. 1741)
- May 11 – Spencer Perceval, Prime Minister of the United Kingdom (assassinated) (b. 1762)
- May 12 – Martha Ballard, American diarist and midwife (b. 1734 or 1735)
- May 18 – John Bellingham, British assassin of Spencer Perceval (b. 1769)
- September 19 – Mayer Amschel Rothschild, German banker (b. 1744)
- September 21 – Emanuel Schikaneder German dramatist, actor, and singer (b. 1751)
- October 13 – Isaac Brock, British general (killed in action) (b. 1769)
- December 20 – Sacagawea, Shoshone guide (b. ca. 1788)
- December 24 – George Beck, American artist and poet (b. 1749)
- "Life in the Desert, or, Recollections of Travel in Asia and Africa". World Digital Library. 1860. Retrieved 2013-09-23.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>