Scott graduated from West Point in 1876 (his Cullum number was 2628), and was commissioned in the Cavalry. For some twenty years thereafter he served on the Western frontier, chiefly with the 7th United States Cavalry. He was assigned to the quarters only recently vacated by the widow of George Armstrong Custer. In fact, Scott was sent out to the Little Big Horn battle site to mark gravesites for Custer's men killed in the battle. He also had the opportunity to interview many of the Native Americans who fought on both sides of the battle on June 25, 1876. He saw action in campaigns against the Sioux, Nez Perce, Cheyenne and other tribes of the Great Plains and became an expert in their languages and ways of life. He was promoted to first lieutenant in June 1878.