Corps of Topographical Engineers
From 1777 to 1863, topographical engineers were used in the United States Army. In 1813, Congress authorized eight officers to be a part of the general staff. Each was to have the brevet rank and pay of a major in the U.S. Cavalry. They also authorized eight assistants, each with the brevet rank and pay of a captain in the U.S. Infantry. They formed the Topographical Bureau as a branch of the U.S. Army Corps of Engineers.