Thomas Mower McDougall subsequently he was appointed Captain, 15 Dec 1875. In 1876 Captain McDougall commanded Company B and accompanied the 7th Cavalry Regiment, under command of Lt. Col. George A. Custer in its fateful departure from Fort Abraham Lincoln to participate in what became known as the Great Sioux War of 1876, which culminated in the Battle of the Little Bighorn, also known as Custer's Last Stand which occurred on June 25–26, 1876. On May 17, 1876, the 7th Cavalry left their base at Fort Abraham Lincoln near present day Mandan, North Dakota to join in a campaign against the Sioux Indians.
Battle of Slim Buttes June 17, 1876, beat off the Indian attack, driving the Sioux northward as contemplated in Sheridan's plan. From that point of view it was regarded as a victory. Crook had seriously wounded men to care for, His supplies of food and ammunition were used up. Therefore, he fell back to Goose Creek to reorganize." Custer's 7th Cavalry regiment was a major component of General Terry's column. Custer ascended the Little Big Horn in search of an Indian village and attacked on June 26, 1876. "No one had any idea that all of the Indians would be found in one spot