[President Abraham Lincoln, Major General John A. McClernand (right), and E. J. Allen (Allan Pinkerton, left), Chief of the Secret Service of the United States, at Secret Service Department, Headquarters Army of the Potomac, near Antietam, Maryland], October 3, 1862, Albumen silver print from glass negative, Image: 20 x 18.5 cm (7 7/8 x 7 5/16 in.), Photographs, Alexander Gardner (American, Glasgow, Scotland 1821–1882 Washington, D.C.).
[President Abraham Lincoln, Major General John A. McClernand (right), and E. J. Allen (Allan Pinkerton, left), Chief of the Secret Service of the United States, at Secret Service Department, Headquarters Army of the Potomac, near Antietam, Maryland], October 3, 1862, Albumen silver print from glass negative, Image: 20 x 18.5 cm (7 7/8 x 7 5/16 in.), Photographs, Alexander Gardner (American, Glasgow, Scotland 1821–1882 Washington, D.C.)