1st January » The Bishop of Durham, Shute Barrington, orders troops from Durham Castle to break up a miners strike in Chester-le-Street, Co. Durham
19th January » Peninsular War: After a ten-day siege, Arthur Wellesley, 1st Duke of Wellington, orders British soldiers of the Light and third divisions to storm Ciudad Rodrigo.
7th February » The New Madrid Earthquake or strongest in a series of earthquakes strikes New Madrid, Missouri.
11th February » Massachusetts governor Elbridge Gerry "gerrymandering known as gerrymanders" for the first time.
27th February » Argentine War of Independence: Manuel Belgrano raises the Flag of Argentina in the city of Rosario for the first time.
27th February » Poet George Gordon Byron, 6th Baron Byron e.g 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.
16th March » Battle of Badajoz (1812) Battle of Badajoz (March 16 April 6) Great Britain British and Portugal Portuguese forces besieged and defeated France French garrison during Peninsular War.
19th March » The Cádiz Cortes promulgates the Spanish Constitution of 1812.
26th March » An 1812 Caracas earthquake e.g earthquake destroys Caracas, Venezuela.
26th March » A political cartoon in the 'Boston Gazette' coins the term "gerrymander" to describe oddly shaped electoral districts designed to help incumbents win reelection.
27th March » Hugh McGary Jr. establishes what is now Evansville, Indiana on a bend in the Ohio River.
4th April » President of the United States or U.S. President James Madison enacts a ninety-day embargo on trade with the United Kingdom.
6th April » British forces under the command of the Duke of Wellington assault the fortress of Siege of Badajoz (1812) known as Badajoz. This would be the turning point in the Peninsular War against Napoleon-led France.
30th April » The Territory of Orleans becomes the 18th U.S. state under the name Louisiana.
11th May » Prime Minister of the United Kingdom named Prime Minister Spencer Perceval is assassinated by John Bellingham in the lobby of the British House of Commons known as House of Commons, London.
16th May » Russian Field Marshal Mikhail Kutuzov signs the Treaty of Bucharest (1812) called Treaty of Bucharest, ending the Russo-Turkish War (1806–12) or Russo-Turkish War. Bessarabia is annexed by Imperial Russia.
18th May » John Bellingham is found guilty and sentenced to death by hanging for the assassination of British Prime Minister Spencer Perceval.
22nd May » Action of 22 May 1812: A small French two-frigate squadron comprising French frigate Ariane (1811) 'Ariane' and French frigate Andromaque (1811) 'Andromaque', returning from a commerce raiding campaign in the Atlantic, meets the 74-gun HMS Northumberland
1st June » War of 1812: The President of the United States called U.S. President James Madison asks the Congress of the United States named Congress to declare war on the United Kingdom.
18th June » War of 1812: The Congress of the United States named U.S. Congress declares war on Kingdom of Great Britain named Great Britain, Canada, and Ireland.
23rd June » War of 1812: Great Britain revokes the restrictions on United States known as American commerce, thus eliminating one of the chief reasons for going to war.
12th July » War of 1812: The United States invades Canada at Windsor, Ontario.
18th July » The Treaty of Orebro Treaties of Orebro ends both the Anglo-Russian War (1807–1812) Anglo-Russian and Anglo-Swedish War (1810–1812) Anglo-Swedish Wars.
22nd July » Napoleonic Wars: Peninsular War Battle of Salamanca United Kingdom British forces led by Arthur Wellesley, 1st Duke of Wellington Arthur Wellesley (later the Duke of Wellington) defeat France French troops near Salamanca, Spain.
11th August » Peninsular War: French troops engage United Kingdom e.g British-Portugal named Portuguese forces in the Battle of Majadahonda.
15th August » War of 1812: The Battle of Fort Dearborn is fought between United States troops and Potawatomi at what is now Chicago called Chicago, Illinois.
16th August » War of 1812: American General William Hull surrenders Fort Shelby (Michigan) known as Fort Detroit Siege of Detroit called without a fight to the British Army.
19th August » War of 1812: American frigate USS Constitution USS Constitution vs HMS Guerriere defeats the British frigate HMS Guerriere 1806 6 off the coast of Nova Scotia, Canada earning the nickname "Old Ironsides".
24th August » Peninsular War: A coalition of Spanish, United Kingdom of Great Britain and Ireland or British, and Kingdom of Portugal called Portuguese forces succeed in lifting the two-and-a-half-year-long Siege of Cádiz.
3rd September » Twenty-four settlers are killed in the Pigeon Roost State Historic Site Pigeon Roost Massacre e.g Pigeon Roost Massacre in Indiana.
4th September » War of 1812: The Siege of Fort Harrison begins when the fort is set on fire.
7th September » French invasion of Russia : The Battle of Borodino, the bloodiest battle of the Napoleonic Wars, was fought near Moscow and resulted in a French victory.
13th September » War of 1812: A supply wagon sent to relieve Siege of Fort Harrison named Fort Harrison is ambushed in the Siege of Fort Harrison Attacks at the Narrows e.g Attack at the Narrows.
14th September » Napoleonic Wars: The French Grande Armée enters Moscow. The Fire of Moscow (1812) or Fire of Moscow begins as soon as Russian troops leave the city.
15th September » The French army under Napoleon reaches the Moscow Kremlin called Kremlin in Moscow.
15th September » War of 1812: A second supply train sent to relieve Siege of Fort Harrison called Fort Harrison is ambushed in the Battle of Fort Harrison Attacks at the Narrows or Attack at the Narrows.
16th September » The Fire of Moscow (1812) or Fire of Moscow begins shortly after midnight and destroys three quarters of the city days later.
18th September » Fire of Moscow (1812) or The 1812 Fire of Moscow dies down after destroying more than three-quarters of the city. Napoleon returns from the Petrovsky Palace to the Moscow Kremlin, spared from the fire.
9th October » War of 1812: In a naval engagement on Lake Erie, American forces capture two British ships: HMS Detroit 1812 6 and HMS Caledonia (1807) HMS 'Caledonia'.
13th October » War of 1812: Battle of Queenston Heights As part of the Niagara campaign in Ontario, Canada, United States forces under General Stephen Van Rensselaer III known as Stephen Van Rensselaer are repulsed from invading Canada by United Kingdom known as British
19th October » Napoleon I of France retreats from Moscow.
23rd October » Claude François de Malet, a French general, Malet coup of 1812 known as begins a conspiracy to overthrow Napoleon I of France known as Napoleon Bonaparte, claiming that the Emperor died in Russia and that he is now the commandant of Paris.
24th October » Napoleonic Wars: The Battle of Maloyaroslavets takes place near Moscow.
25th October » War of 1812: The American frigate, USS United States 1797 6, commanded by Stephen Decatur, USS United States vs HMS Macedonian captures the British frigate HMS Macedonian.
22nd November » War of 1812: 17 Indiana Rangers are killed at the Battle of Wild Cat Creek.
14th December » The French invasion of Russia comes to an end as the remnants of the Grande Armée are expelled from Russia.
17th December » War of 1812: U.S. forces attack a friendly Lenape village in the Battle of the Mississinewa.
29th December » The USS Constitution USS 'Constitution' under the command of Captain (United States O-6) Captain William Bainbridge, captures the HMS Java (1811) HMS 'Java' off the coast of Brazil after a three hour battle.