Here are some of the more significant dates and events of the Civil War, in which 617,000 people died.
Oct. 16-18: John Brown, in an attempt to amass arms for a slave insurrection, attacks the federal armory and arsenal at Harpers Ferry, Va.
Dec. 2: Brown is hanged for murder and treason at Charles Town, Va.
Nov. 6: Abraham Lincoln is elected president, with Hannibal Hamlin as his vice president.
Dec. 20: As a consequence of Lincoln's election, a special convention of the South Carolina legislature votes to secede from the Union.
Jan. 9-Feb. 1: Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas follow South Carolina's lead and secede from the Union.
March 4: Abraham Lincoln is inaugurated as the 16th president of the United States.
April 17: May 20: Virginia, Arkansas, Tennessee, and North Carolina secede from the Union.
Sept. 22: President Lincoln issues the Preliminary Emancipation Proclamation.
Jan. 1: Lincoln issues the Emancipation Proclamation, which declares that slaves in the seceded states are now free.
July 1-3: The Battle of Gettysburg is fought in Pennsylvania. General George G. Meade compromises his victory by allowing Lee to retreat South across the Potomac.
Nov. 19: Lincoln delivers his Gettysburg Address, in which he reiterates the nation's fundamental principle that all men are created equal.
June 28: Lincoln signs a bill repealing the fugitive slave laws.
Nov. 8: Lincoln is re-elected pPresident, with Andrew Johnson as vice president.
Jan. 31: Congress passes the Thirteenth Amendment, which abolishes slavery throughout the United States.
March 4: Lincoln is inaugurated as president for a second term.
April 14: John Wilkes Booth shoots President Lincoln at Ford's Theater; Secretary of State William H. Seward is stabbed and wounded in an assassination attempt inside his Washington home.
April 15: Lincoln dies, and Andrew Johnson is inaugurated as President.
April 18: The Confederate Army surrenders, and the Civil War ends.
Source: The Smithsonian Institution