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.
George Armstrong Custer Hills region from the Sioux. When the Sioux refused to sell, they were ordered to report to reservations by the end of January, 1876. Mid-winter conditions made it impossible for them to comply. The administration labeled them "hostiles" and tasked the Army with bringing them in. Custer was to command an expedition planned for the spring, part of a three-pronged campaign. While Custer's expedition marched west from Fort Abraham Lincoln, near present-day Mandan, North Dakota, troops under Colonel John Gibbon were to march east from Fort Ellis, near present-day Bozeman, Montana while a force under General George Crook was to