Andrew Atkinson Humphreys, an American soldier, born in Pennsylvania about 1812. He graduated at West Point in 1831, and served mainly in topographical duty till 1836, when he resigned his commission in the army, and became a civil engineer in the United States service. In 1838 he was reappointed in the army, serving generally in the topographical department, and from 1844 to 1849 had charge of the coast survey office at Washington. In 1849-'50 he was engaged in making topographic and hydrographic surveys of the delta of the Mississippi, continuing in general charge of the work till 1861, when he published a voluminous and very valuable "Report upon the Physics and Hydraulics of the Mississippi River." During the civil war he was on the staff of McClellan until his supersedure by Burnside, was made brevet colonel for his services in the battle of Fredericksburg, commanded a division at Chancellorsville and at Gettysburg, and after the last battle became chief of the staff of Gen. Meade, being appointed major general of volunteers, July 8, 1863. He took an active part in the campaigns of 1864 and 1865, succeeding Hancock in the command of the 2d corps.

He was brevetted brigadier general in the regular army for gallant conduct at Gettysburg, and major general for services at the battle of Sailor's Creek, the closing battle of the war (April 7, 1865). From July to December, 1865, he commanded the district of Pennsylvania, and thereafter he was in charge of the examination of the Mississippi levees till August, 1866, when he was appointed chief of engineers of the United States army, with the rank of brigadier general.