Barton Stone Alexander (September 4, 1819 – December 15, 1878) was a Union Army lieutenant colonel, engineer regiment commander and chief engineer for the defenses of Washington during the American Civil War. In recognition of his service, in 1866, he was appointed to the brevet rank of brigadier general in the regular army, to rank from March 13, 1865. He was a graduate of the U.S. Military Academy at West Point and served in the United States Army's Corps of Topographical Engineers, which at times was both a part of and separate from the United States Army Corps of Engineers. After graduating from West Point as a second lieutenant in the Class of 1842, he served in the Mexican–American War, building fortifications to protect American supply lines in the advance on Mexico City. After the