Group at Secret Service headquarters at Antietam, Maryland. (Title from paper accompanying photograph) Photograph shows fourteen men, including Allan and William Pinkerton, and several Union Army officers posed in front of a tent. Below each is a hand-written number which corresponds to a list on the back of the mount which identifies the men in the photograph: 1. Wm. Pinkerton 2. Geo. Washington (Cook) 3. Harry Thomas 4. A. E. Keneaster 5. Lt. Col. Calhoun, A.D.C. 6. Capt. McLellan, A.D.C. 7. Sidney Denning 8. Chas. Hazzlett, Postmaster 9. Allan Pinkerton 10. Geo. H. Bangs 11. Col. Howard, A.D.C. 12. Mr. Kennedy of the War Dept. 13. Chas. Gerald 14. A. K. Littlefield. Credit: Library of Congress.

Group at Secret Service headquarters at Antietam, Maryland. (Title from paper accompanying photograph) Photograph shows fourteen men, including Allan and William Pinkerton, and several Union Army officers posed in front of a tent. Below each is a hand-written number which corresponds to a list on the back of the mount which identifies the men in the photograph: 1. Wm. Pinkerton 2. Geo. Washington (Cook) 3. Harry Thomas 4. A. E. Keneaster 5. Lt. Col. Calhoun, A.D.C. 6. Capt. McLellan, A.D.C. 7. Sidney Denning 8. Chas. Hazzlett, Postmaster 9. Allan Pinkerton 10. Geo. H. Bangs 11. Col. Howard, A.D.C. 12. Mr. Kennedy of the War Dept. 13. Chas. Gerald 14. A. K. Littlefield. Credit: Library of Congress.

Group at Secret Service headquarters at Antietam, Maryland. (Title from paper accompanying photograph) Photograph shows fourteen men, including Allan and William Pinkerton, and several Union Army officers posed in front of a tent. Below each is a hand-written number which corresponds to a list on the back of the mount which identifies the men in the photograph: 1. Wm. Pinkerton 2. Geo. Washington (Cook) 3. Harry Thomas 4. A. E. Keneaster 5. Lt. Col. Calhoun, A.D.C. 6. Capt. McLellan, A.D.C. 7. Sidney Denning 8. Chas. Hazzlett, Postmaster 9. Allan Pinkerton 10. Geo. H. Bangs 11. Col. Howard, A.D.C. 12. Mr. Kennedy of the War Dept. 13. Chas. Gerald 14. A. K. Littlefield. Credit: Library of Congress.

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