Input (grade 9): As a staff officer for Major General George B. McClellan, Custer was promoted to the rank of Captain during the Army of the Potomac's 1862 Peninsula Campaign.
Output (grade 8): Custer graduated last in his class and served at the First Battle of Bull Run as a staff officer for Major General George B. McClellan in the Army of the Potomac's 1862 Peninsula Campaign.