In the post-Civil War Southwest, the United States Army utilized civilians and Indians as scouts. As the mainstay of the reconnaissance force, enlisted Indians excelled as trackers, guides, and fighters. General George Crook became the foremost advocate of this service. A little-known aspect of the era was the international controversy created by the activities of native trackers under the 1882 reciprocal hot pursuit agreement between Mexico and the United States. Providing valuable information on Army scouts are numerous government records which include the Annual Report of the Secretary of War from 1866 to 1896 and Foreign Relations of the United States for 1883 and 1886. Memoirs, biographies, and articles in regional and national historical journals supplement government documents.