A newly discovered 150-year-old map of the Civil War’s Battle of Antietam shows thousands of graves of Union and Confederate soldiers killed near Sharpsburg, Md., in 1862.

A climate activist with a radical protest group smeared red paint on a Civil War exhibit honoring Black soldiers killed during a key 1863 battle.

They also note that, after the Civil War, Mosby befriended Union Gen. Ulysses S. Grant and expressed regret over his role in the Southern cause to maintain slavery, making his legacy more complicated.

The Civil War transformed Washington from a sleepy outpost into a federal city, its population nearly doubling between 1860 and 1870. Photograph courtesy of Library of Congress. During the two years I ...