Military officer; born in
New Haven, Conn., Dec. 22, 1803; graduated at
West Point in 1822, and entered the engineer corps.
He served as chief engineer under
General Taylor in the war against
Mexico, and was brevetted colonel for his services there.
In 1853 he was inspectorgeneral, with the rank of colonel; and in May, 1861, he was made brigadier-general, and placed in command of the Department of Washington; and, for a while, that of
Virginia.
General Mansfield thoroughly fortified the national capital, and, after various services, was promoted major-general of volunteers, July 18, 1862, and took command of the corps formerly under
General Banks.
With that he went into the
battle of Antietam, and was mortally wounded early in the day, dying Sept. 18.