January 1 – Abraham Lincoln signs the Emancipation Proclamation during the third year of the American Civil War, making the abolition of slavery in the Confederate States of America an official war goal. The signing proclaimed the freedom of 3.1 million of the nation's four million slaves and immediately frees 50,000 of them, with the rest freed as the Union Army advances. This event marks the start of America's Reconstruction Era.
January 2 – Master Lucius Tar Paint Company ( Teerfarbenfabrik Meister Lucius), predecessor of Hoechst AG, as a worldwide Chemical, founded in a suburb of Frankfurt am Main, Germany.
January 4 – Founding date of the New Apostolic Church, a Christian and chiliastic church, in a schism with the Catholic Apostolic Church in Hamburg, Germany.
January 7 – In the Swiss canton of Ticino, the village of Bedretto is partly destroyed and 29 killed by an avalanche.
January 8
The Yorkshire County Cricket Club is founded at the Adelphi Hotel, in Sheffield, England.
American Civil War: The Second Battle of Springfield takes place near Springfield, Missouri. Fighting for the Union, General Egbert B. Brown leads the Missouri militia to victory over Confederate General John S. Marmaduke and the 18th Arkansas Infantry.
January 10 – The first section of the London Underground Railway (Paddington to Farringdon Street) opens officially.
January 11
American Civil War: Battle of Arkansas Post – General John McClernand and Admiral David Dixon Porter capture the Arkansas River for the Union.
In the Swiss canton of Ticino, the roof of the church of Sant'Antonio in Locarno collapses under the weight of snow, killing 47.
January 15 – French intervention in Mexico: French forces bombard Veracruz.
January 21 – Adam Opel founds Opel in Germany, originally for the manufacture of sewing machines.
January 22 – The January Uprising breaks out in Poland, Lithuania and Belarus. The aim of the national movement is to liberate the Polish–Lithuanian–Ruthenian Commonwealth from Russian occupation.
January 29 – American Indian Wars – Bear River Massacre: The United States Army, led by General Patrick Edward Connor, massacres Chief Bear Hunter and forces of the Shoshone, in the Idaho Territory.
January 31 – Jules Verne's first adventure novel, Five Weeks in a Balloon ( Cinq semaines en ballon), is published in Paris.
February 1 – Radicals in Lithuania, Belarus, Latvia, northern Ukraine and western Russia join the January Uprising.
February 2 – January Uprising: Polish peasants are massacred by Russian hussars at Čysta Būda, near Marijampolė.
February 7 – sinks while attempting to enter Manukau Harbour in New Zealand, with the loss of 189 lives.
February 10 – Alanson Crane of Virginia patents a fire extinguisher.
February 17 – The "Committee of the Five" holds their first meeting in Geneva, Switzerland, which is regarded as the foundation of the International Committee of the Red Cross, following the lead of humanitarian businessman Henry Dunant.
Pierre Boissier (1985). 9782880440121, Henry Dunant Institute. ISBN 9782880440121
February 24 – Arizona is organized as a United States territory.
February 26 – Abraham Lincoln signs the National Banking Act into law.
March 19 – The is destroyed on her maiden voyage while attempting to run the blockade into Charleston, South Carolina. The wreck is discovered exactly 102 years later, by E. Lee Spence.
March 25 – U.S. Army Private Jacob Parrott, a soldier in "Andrews' Raiders", becomes the first person to receive the Medal of Honor, presented by U.S. Secretary of War Edwin M. Stanton to six of the Raiders. Parrott is followed that day by six others.
March 30 – Prince Wilhelm George of Denmark is elected at the age of 17 by the Hellenic Parliament as George, King of the Hellenes; he will reign in Greece for 50 years. He arrives in Athens on October 30 to take the throne.
April 13 – The Winged Victory of Samothrace, one of the most significant sculptures of classical antiquity, is found in excavations on the Greek island of Samothrace by Charles Champoiseau. Made c.190 BC, it is shipped to the Louvre in Paris.
April 14 – The Treaty of Huế is signed between Vietnam and the French Empire.
April 17–May 2 – American Civil War: Grierson's Raid – Union cavalrymen are ambushed while crossing the Tickfaw River in Mississippi.
April 20
American Civil War: The Battle of Washington ends inconclusively in Beaufort County, North Carolina.
The Augustus of Prima Porta, one of the most significant sculptures of classical antiquity, is found in excavations in the Villa of Livia at Prima Porta, near Rome.
April 21
Ayyam-i butun: Bahá'u'lláh begins a 12-day stay in the Najibiyyih gardens, Baghdad (later known as the Garden of Ridván) during which he declares his station as He whom God shall make manifest. This date is celebrated in the Baháʼí Faith as the festival of Ridván.
January Uprising: The Polish peasant army, now led by Zygmunt Sierakowski, achieves its first victory over the Russian army, near Raguva.
April 24 – The Lieber Code signed and issued by President Abraham Lincoln to the Union forces of the United States in the American Civil War constitutes the world's first official comprehensive code of the modern laws of war.
April 30 – Battle of Camarón in Mexico: 65 soldiers of the French Foreign Legion fight 2,000 Mexicans.
May 1–4 – American Civil War: Battle of Chancellorsville – General Robert E. Lee defeats Union forces with 13,000 Confederate casualties, among them Stonewall Jackson (fatally wounded by friendly fire), and 17,500 Union casualties.
May 8
The Granadine Confederation becomes the United States of Colombia, under President Tomás Cipriano de Mosquera.
January Uprising: The Polish insurgent army is defeated by the Russians near Gudiškis.
May 14 – American Civil War: Battle of Jackson, Mississippi – Union General Ulysses S. Grant defeats Confederate General Joseph E. Johnston, opening the way for the siege of Vicksburg.
May 17
After a 2-month siege, the French army of Achille Bazaine takes Puebla, Mexico.
The opening of Salon des Refusés in Paris draws attention to paintings by avant-garde artists, notably Manet's_ Le Déjeuner sur l’herbe.
May 18 – American Civil War: The siege of Vicksburg begins (ends July 4, when 30,189 Confederate men surrender).
May 21 –
American Civil War: The siege of Port Hudson, Louisiana, by Union forces begins.
The General Conference of Seventh-day Adventists is formed in Battle Creek, Michigan.
May 23 – Ferdinand Lassalle founds the Allgemeiner Deutscher Arbeiterverein (General German Workers' Association, ADAV), the first socialist workers party in Germany.
May 27 – Afghan Civil War (1863-1869): Herat is captured by the forces of Dost Mohammad Khan.
May 28 – American Civil War: The 54th Massachusetts, the first African-American regiment, leaves Boston to fight for the Union.
May 31 – The first Prix de l'Arc de Triomphe horse race is held.
June 7 – French intervention in Mexico: French forces enter Mexico City.
June 9 – American Civil War: The Battle of Brandy Station, Virginia, ends inconclusively.
June 12 – The Arts Club is founded by Charles Dickens, Frederic Leighton and others in Hanover Square, London.
June 13 – Samuel Butler's article "Darwin among the Machines" is published (under the pen name Cellarius) in The Press newspaper in Christchurch, New Zealand; it will be incorporated into his novel Erewhon (1872).
American Civil War:
June 14 – Second Battle of Winchester – A United States garrison is defeated by the Army of Northern Virginia in the Shenandoah Valley town of Winchester, Virginia.
June 17 – The Battle of Aldie in the Gettysburg Campaign ends inconclusively.
June 20 – West Virginia is admitted as the 35th U.S. state.
Slavery is abolished in the Dutch Empire of Suriname (independent from 1975) and Curaçao and Dependencies.
The Kingston loop line of the London and South Western Railway opens.
American Civil War:
July 1–3 – Battle of Gettysburg – Union forces under George G. Meade turn back a Confederate invasion by Robert E. Lee in the largest battle of the war (28,000 Confederate casualties, 23,000 Union).
July 4 – Siege of Vicksburg – Ulysses S. Grant and the Union army capture the Confederate city Vicksburg, Mississippi, after the town surrenders following a 47-day siege.
July 9 – American Civil War: The Siege of Port Hudson ends, and the Union controls the entire Mississippi River for the first time.
July 13 – New York City draft riots: In New York City, opponents of conscription to the American Civil War begin 3 days of violent rioting, which will be regarded as the worst in the history of the United States with around 120 killed.
July 16 – Battle of Shimonoseki Straits: The screw sloop engages with the Chōshū Domain fleet before withdrawing, in Japan's first naval engagement between elements of modern navies.
July 17 – The New Zealand Wars against the Māori people resume, as British forces in New Zealand led by Duncan Cameron begin their Invasion of the Waikato.
American Civil War:
July 17 – Battle of Honey Springs – Union troops win a strategic victory over the Confederates for control of Indian Territory north of the Arkansas River.
July 18 – The first formal African American military unit, the 54th Massachusetts Volunteer Infantry, unsuccessfully assaults Confederate-held Fort Wagner but their valiant fighting still proves the worth of African American soldiers during the war. Their commander, Colonel Robert Shaw, is shot leading the attack, and is buried with his men (450 Union, along with 175 Confederate).
July 26 – American Civil War: Morgan's Raid – At Salineville, Ohio, Confederate cavalry leader John Hunt Morgan and 375 of his volunteers are captured by Union forces.
July 30 – American Indian Wars: Representatives of the United States and tribal leaders including Chief Pocatello (of the Shoshone) sign the Box Elder Treaty.
July 30 – Valuev Circular bans the publication of religious, educational and training books in Ukrainian in the Russian Empire.
At the suggestion of Senator J. V. Snellman and the order of Emperor Alexander II, full rights are promised to the Finnish language by a language regulation in the Grand Duchy of Finland.
August 3 – Otago Boys' High School is founded in New Zealand.
August 8 – American Civil War: Following his defeat in the Battle of Gettysburg, General Robert E. Lee sends a letter of resignation to Confederate President Jefferson Davis (Davis refuses the request upon receipt).
August 15–17 – Bombardment of Kagoshima: The British Royal Navy bombards the town of Kagoshima in Japan in retribution, after the Namamugi Incident of 1862.
August 16 – After Spain's annexation of the Dominican Republic, rebels raise the Dominican flag in Santiago to begin the Dominican Restoration War.
American Civil War:
August 17 – In Charleston, South Carolina, Union batteries and ships bombard Confederate-held Fort Sumter (the bombardment does not end until December 31).
August 21 –
Battle of Lawrence: Lawrence, Kansas, is attacked by William Quantrill's raiders, who kill an estimated 200 men and boys. The raid becomes notorious in the North as one of the most vicious atrocities of the Civil War.
The American clipper ship Anglo Saxon (westbound) is captured and burned by Confederate privateerFlorida off the south coast of Ireland.
Daniel J. Nolan (2025). 9781908726001, Malbay Publishing. ISBN 9781908726001
October 3 – U.S. President Abraham Lincoln proclaims a national Thanksgiving Day, to be celebrated on the final Thursday in November.
October 5 – The Brooklyn, Bath and Coney Island Rail Road starts operations in Brooklyn, New York, making it the oldest right-of-way on the New York City Subway, the largest rapid transit system in the United States, and one of the largest in the world.
American Civil War:
October 14 – Battle of Bristoe Station – Confederate General Robert E. Lee's forces fail to drive the Union army out of Virginia.
October 15 – The Confederate submarine H. L. Hunley sinks during a test, killing Horace Lawson Hunley (its inventor) and a crew of seven.
October 26–29 – The Resolutions of the Geneva International Conference are signed by sixteen countries meeting in Geneva agreeing to form the International Red Cross.
October 29 – American Civil War: Battle of Wauhatchie – Forces under Union General Ulysses S. Grant, having fought through the night, ward off a Confederate attack led by General James Longstreet. Union forces thus open a supply line into Chattanooga, Tennessee.Cozzens, Peter. The Shipwreck of Their Hopes: The Battles for Chattanooga. Urbana: University of Illinois Press, 1994. . Page 100.
November 4 – Hector Berlioz's opera Les Troyens is performed for the first time, at the Théâtre Lyrique in Paris.
Robert Ignatius Letellier (2010). 9781443821681, Cambridge Scholars Publishing. . ISBN 9781443821681
November 15 – King Christian IX of Denmark succeeds his distant cousin Frederick VII, giving rise to the beginning of the Second Schleswig-Holstein crisis.
American Civil War:
November 16 – Battle of Campbell's Station – Near Knoxville, Tennessee, Confederate troops led by General James Longstreet unsuccessfully attack Union forces under General Ambrose Burnside.
November 17 – Siege of Knoxville – Confederate forces led by General James Longstreet place Knoxville, Tennessee, under siege (the two-week-long siege and an attack are unsuccessful).
November 18 – King Christian IX of Denmark signs the November Constitution, which declares Schleswig to be part of Denmark, regarded by the German Confederation as a violation of the London Protocol of 1852, leading to the German–Danish war of 1864.
November 19 – U.S. President Abraham Lincoln delivers the Gettysburg Address, at the military cemetery dedication ceremony in Gettysburg, Pennsylvania.
American Civil War:
November 23 – Battle of Chattanooga III – Union forces led by General Ulysses S. Grant reinforce troops at Chattanooga, Tennessee, and counter-attack Confederate troops.
November 24 – Battle of Lookout Mountain – Near Chattanooga, Tennessee, Union forces under General Ulysses S. Grant capture Lookout Mountain, and begin to break the Confederate siege of the city, led by General Braxton Bragg.
November 25 – Battle of Missionary Ridge – At Missionary Ridge in Tennessee, Union forces led by General Ulysses S. Grant break the siege of Chattanooga, by routing Confederate troops under General Braxton Bragg.
November 26 – Mine Run – Union forces under General George Meade position against troops led by Confederate General Robert E. Lee (Meade's forces cannot find any weaknesses in the Confederate lines, and give up trying after five days).
November 27 – Confederate cavalry leader John Hunt Morgan and several of his men escape the Ohio state prison, and return safely to the South.
December 1 – The first steam-operated passenger railway in New Zealand opens at Christchurch in South Island.
December 6 – C.S.A.C. Fides Quadrat Intellectum, the First Reformed student society, is founded at the Theologische Universiteit Kampen (Broederweg), in Kampen, the Netherlands.
December 8 – The Church of the Company Fire in Santiago, Chile, kills between 2,000 and 3,000 people.
