Gettysburg pictures from the National Archives

The Battle of Gettysburg was one of the costliest military engagements in American history, in part because those on both sides were Americans. The three-day battle, the turning point of the Civil War, began July 1, 1863 - 150 years ago.

At left, an undated picture from the National Archives shows U.S. Army Gen. John C. Robinson.

This undated picture shows the headquarters for the Army of the Potomac during the Battle of Gettysburg.

This undated picture from the National Archives shows wounded soldiers from the Battle of Gettysburg.

This undated picture from the National Archives shows a view of Gettysburg, Pa., during the Civil War.

This undated picture from the National Archives shows soldiers standing with President Abraham Lincoln at the site of the Battle of Gettysburg.

This undated picture from the National Archives shows Barlow's Knoll after the first day of the battle.

This undated picture from the National Archives shows three "Johnnie Reb" Confederate prisoners on Seminary Ridge during the Battle of Gettysburg.

This 1938 picture from the National Archives shows Union and Confederate soldiers shaking hands over a stone wall during a reunion of "the blue and the grey."

This undated picture from the National Archives shows a view of the "slaughter pen."