American Troops Posing with a Gatling Gun at Fort McKeen in North Dakota (1880)

Animated stereoview version.

American troops posing with a Gatling gun at Fort McKeen in North Dakota, c. 1880. By F. Jay Haynes.

Source.
Harvard Business School source.
North Dakota state government source.

Two Views of Union Soldiers Posing With an Office Wagon Used by the Headquarters of the Army of the Cumberland During the Civil War

Two views of Union soldiers posing with an office wagon used by the headquarters of the Army of the Cumberland at Chattanooga, Tennessee, during the Civil War.

Source 1.
Source 2.