David Barnum is listed as a non-graduate of the U. S. Naval Academy Class of 1863 which was ordered into active service May 1861, two years early.

The bottom 12 men of the 55 graduates resigned to enter Confederate service 19/20 April, 1861, with one resigning February 16.

He was originally a member of the class of 1862 and re-assigned to the class of 1863 on his re-instatement. It would appear he failed academically, not graduating with his class May, 1861. Whereupon he would have been turned back to the next class, ’64, but resigned instead.