Which three-day 1863 battle had the largest number of casualties in the Civil War?

The Battle of Gettysburg was the three-day Civil War battle with the largest number of casualties. Fought from July 1 to July 3, 1863, in and around Gettysburg, Pennsylvania, it ended in a major Union victory over General Robert E. Lee’s Confederate Army of Northern Virginia.

Estimated casualties vary because Confederate records were incomplete, but historians generally place total losses between about 46,000 and 51,000 killed, wounded, captured, or missing. The Union recorded roughly 23,000 casualties, while Confederate losses are often estimated at approximately 23,000 to 28,000.

The battle began when Confederate forces moving through Pennsylvania encountered Union cavalry west of Gettysburg. Fighting spread across nearby ridges and hills, culminating in the Confederate defeat of Pickett’s Charge on July 3. Lee’s army withdrew to Virginia, ending its second major invasion of the North.

Gettysburg is often confused with Antietam, which was the bloodiest single day in American military history. Gettysburg produced more casualties across an entire battle, while Antietam’s losses occurred mainly during one day of fighting on September 17, 1862.