Joseph King Fenno Mansfield was one of the oldest officers on the field at age 59. Born in New Haven, Connecticut, Mansfield graduated from West Point in 1822. A professional soldier, he served in the Army for forty years, including service in the Mexican War. Just two days before the battle, he was given command of the XII Corps. MGen Mansfield led his men through the East Woods towards the Cornfield in support of I Corps already in action. Wounded in the chest he died the next day. There is a monument and a mortuary cannon on the battlefield for MGen Mansfield.

Joseph K. F. Mansfield
1803-1862, Connecticut

Mansfield graduated from West Point in 1822, standing second in a class of forty. He was assigned to the Corps of Engineers and for the next three years planned fortifications for the defense of the harbors and cities on the East Coast. In 1832 he was promoted to 1st lieutenant and in 1838 to captain. Mansfield served in the Mexican War as chief engineer under Maj. Gen. Zachary Taylor. During the war Mansfield received brevets of major and lieutenant colonel for gallant and meritorious conduct. He was appointed inspector general of the U.S. Army in 1853 with the rank of colonel and at the beginning of the Civil War was commissioned brigadier general of volunteers and placed in command of the Department of Washington and the city of Washington. Mansfield was in command of Newport News in late 1861 and was engaged in the capture of Norfolk and Suffolk, Virginia, the following spring. On 18 July he was promoted to major general of volunteers. During the Maryland Campaign in September Mansfield was assigned command of Maj. Gen. Nathaniel P. Banks' XII Corps after Banks was detailed to duty in Washington. Mansfield had been in command only three days when at the Battle of Antietam he was mortally wounded while mistakenly riding between the opposing lines. He died the following morning.

Content From:
The U.S. Army Center of Military History