Students exited the school as BREVET 2nd LIEUTENANTS. They remained so until openings in the regular army gave them a real rank.
Class standings dictate where they would and would not go in their career.
Engineers were the "species of God;" only the top were even considered to be engineers, and not all were excepted. The next were topographical engineers, or "topogs." The rest were filled into the ranks of the artillery, infantry, mounted rifles, and dragoons, which were the bottom of the heap.
Brevets were usually allowed to go home and visit their families before starting their new careers.
The vast majority of the men controlling the Civil War were West Point graduates. And an amazing number of them were from the same class.