The first American ironclad warship, the USS Monitor is launched.

American Civil War: Ulysses S. Grant gives the United States its first victory of the war, by capturing Fort Henry, Tennessee, known as the Battle of Fort Henry.

American Civil War: The U.S. federal government forbids all Union army officers to return fugitive slaves, thus effectively annulling the Fugitive Slave Law of 1850 and setting the stage for the Emancipation Proclamation.

U.S. federal troops occupy Baton Rouge, Louisiana.

The United States and Britain agree to suppress the slave trade.

American Civil War: President Abraham Lincoln reluctantly restores Union General George B. McClellan to full command after General John Pope's disastrous defeat at the Second Battle of Bull Run.

American Civil War: Union General Ambrose Burnside assumes command of the Army of the Potomac, after George B. McClellan is removed.

American Civil War: In the Battle of Cane Hill, Union troops under General John Blunt defeat General John Marmaduke's Confederates.

American Civil War: Abraham Lincoln signs an act that admits West Virginia to the Union, thus dividing Virginia in two.

United States begins its first military draft; exemptions cost $300.

American Civil War: In Charleston, South Carolina, Union batteries and ships bombard Confederate-held Fort Sumter.

American Civil War: Battle of Campbell's Station near Knoxville, Tennessee. Confederate troops unsuccessfully attack Union forces.

American Civil War: Battle of Chattanooga begins – Union forces led by General Ulysses S. Grant reinforce troops at Chattanooga, Tennessee and counter-attack Confederate troops.

American Civil War: Kilpatrick-Dahlgren Raid fails – plans to free 15,000 Union soldiers being held near Richmond, Virginia are thwarted.

During the American Civil War, Union forces led by General William T. Sherman launch an assault on Atlanta, Georgia.

American Civil War: Union General William Tecumseh Sherman burns Atlanta, Georgia and starts Sherman's March to the Sea. thumb is deposed and Brazil becomes a republic.]]

American Civil War: Sherman's March to the Sea: Confederate General John Bell Hood invades Tennessee in an unsuccessful attempt to draw Union General William T. Sherman from Georgia.

American Civil War: Battle of Franklin — The Army of Tennessee led by General John Bell Hood mounts a dramatically unsuccessful frontal assault on Union positions commanded by John McAllister Schofield around Franklin, Tennessee, with Hood lost six generals and almost a third of his troops.

In the United States, Delaware voters reject the Thirteenth Amendment to the U.S. Constitution, and vote to continue the practice of slavery. (Delaware finally ratifies the amendment on February 12, 1901.)

American Civil War: Columbia, South Carolina, is burned as Confederate forces flee from advancing Union forces.

American Civil War: The Siege of Petersburg is broken – Union troops capture the trenches around Petersburg, Virginia, forcing Confederate General Robert E. Lee to retreat.

American Civil War: A day after Union forces capture Richmond, Virginia, U.S. President Abraham Lincoln visits the Confederate capital.

Memorial Day first celebrated in United States at Waterloo, New York.

The Fenians are driven out of Fort Erie, Ontario, into the United States.

The United States takes possession of the, at this point unoccupied, Midway Atoll.

The United States takes control of Midway Island.

United States takes possession of Alaska after purchasing it from Russia for $7.2 million. Celebrated annually in the state as Alaska Day.

At Tremont Temple in Boston, British author Charles Dickens gives his first public reading in the United States.

United States claims Midway Atoll, the first territory annexed outside Continental limits.

Decoration Day (the predecessor of the modern "Memorial Day") is observed in the United States for the first time (By "Commander-in-chief of the Grand Army of the Republic" John A. Logan's proclamation on May 5).

The 14th Amendment to the United States Constitution is ratified guaranteeing African Americans full citizenship and all persons in the United States due process of law.

The Christian holiday of Christmas is declared a federal holiday in the United States.

Louisa Ann Swain of Laramie, Wyoming becomes the first woman in the United States to cast a vote legally after 1807.

In the United States, the Weather Bureau (later renamed the National Weather Service) makes its first official meteorological forecast.

The crewless American ship ''Mary Celeste'' is found by the British brig ''Dei Gratia'' (the ship had been abandoned for nine days but was only slightly damaged).

Levi Strauss and Jacob Davis receive a U.S. patent for blue jeans with copper rivets.

Hawaii signs a treaty with the United States granting exclusive trading rights.

The United States orders all Native Americans to move into reservations.

Indian Wars: In retaliation for the American defeat at the Battle of the Little Bighorn, United States Army troops sack Chief Dull Knife's sleeping Cheyenne village at the headwaters of the Powder River.

Chief Crazy Horse of the Oglala Sioux surrenders to United States troops in Nebraska.