Dwight attended USMA, West Point, NY (where he met Whistler), but never graduated. Instead he went into the cotton manufacturing business. During the Civil War he was a captain in the Fourteenth US Infantry, and a brigadier-general of volunteers. He commanded a brigade of the Nineteenth corps in the operations against Port Hudson, and served on the commission to settle the terms of surrender. At the Red River campaign he was made chief of staff to General Banks.
Cullum Memorial Edition, Register of Graduates and former cadets, United States Military Academy, West Point, 1980; Who Was Who in America, Chicago, 1963, p. 162.