Which battle had the highest total casualties in the Civil War?

The Battle of Gettysburg had the highest total casualties in the Civil War, with roughly 46,000–51,000 Union and Confederate casualties combined.

Fought from July 1–3, 1863, in and around Gettysburg, Pennsylvania, the battle stopped Robert E. Lee’s second invasion of the North. Union forces under George G. Meade defeated Lee’s Army of Northern Virginia, making Gettysburg a major turning point in the war.

The casualty total includes soldiers killed, wounded, captured, or missing—not deaths alone. Confederate records are incomplete, so estimates vary, but Gettysburg still ranks above Chickamauga, Spotsylvania Court House, and other major battles. Antietam is often confused with Gettysburg because it produced the war’s bloodiest single day, September 17, 1862, with about 23,000 casualties.