Thomas Custer in the Yellowstone Expedition of 1873, where he fought in the Battle of Honsinger Bluff, and the Black Hills Expedition of 1874. Custer was appointed captain in 1875 and given command of Company C of the 7th Cavalry. In 1874, at the trading post at Standing Rock Agency, Custer participated in the arrest of chief Rain-in-the-Face (Lakota), suspected in the 1873 murder of Dr. John Honsinger. During the 1876 Little Bighorn campaign of the Black Hills War, he served as aide-de-camp to his older brother Lt. Col. George A. Custer and died with his brother on June 25, 1876. Lt.
Battle of the Little Bighorn Sitting Bull's ranks for the summer buffalo hunt. The agents did not take into account the many thousands of these "reservation Indians" who had unofficially left the reservation to join their "uncooperative non-reservation cousins led by Sitting Bull". Thus, Custer unknowingly faced thousands of Indians, including the 800 non-reservation "hostiles". All Army plans were based on the incorrect numbers. Although Custer was severely criticized after the battle for not having accepted reinforcements and for dividing his forces, it must be understood that he had accepted the same official government estimates of hostiles in the area which Terry and Gibbon had