United States President Abraham Lincoln.

President Abraham Lincoln visits Union General George B. McClellan on October 3, 1862, three weeks after the Battle of Antietam.

Unidentified African American soldier in a Union uniform with his wife and two daughters. Some 180,000 African Americans fought in the war, almost exclusively for the Union. Nearly 40,000 of them died.

General William Tecumseh Sherman and staff (from left to right): Generals Oliver O. Howard, John A. Logan, William B. Hazen, Sherman, Jefferson Davis, Henry W. Slocum, and Joseph Mower.

Union General Ulysses S. Grant meets with his general staff, including George Meade, on May 21, 1864, during the Overland Campaign.

Confederate President Jefferson Davis.

Unidentified girl in a mourning dress holding a framed photograph of her cavalryman father. Nearly 620,000 soldiers died during the war, almost 2 percent of the entire population of the United States at the time.

Confederate General Robert E. Lee.

Union General Ulysses S. Grant.