Gen. Crook’s medical director on the 1876 Bighorn and Yellowstone Expedition. In the aftermath of the fight at Slim Buttes, Sept. 9, 1876, Clements performed surgery in the field while Crazy Horse led desperate forays to rescue non-combatants from American Horse’s sacked village. Clements later wrote one of the most important accounts of the Great Sioux War . Original sepia 2.5 x 4 Matthew Brady CDV photo (so printed on reverse), signed on the reverse in black ink, “Dr. B. A. Clements, November 8th, 1862.” In fine condition, with scattered toning and soiling to both sides, pencil notation to bottom of reverse, and Clements boldly signing over an unsuccessful first attempt. R&R COA.