This unnamed Britannian Commander was a high ranking Britannian Military commander who was present during the Battle of Babel Tower and took direct orders from the Emperor. He confronted Lelouch along with his soldiers in an area within Babel Tower and read out all his daily doings, then planned on killing them. Although C.C. gave Lelouch his Geass and memories back. Lelouch then commanded the commander and his men to commit suicide, so they gunned themselves down.
This commander also owns a title of Nobility: Baron, as he claims his a baron to Lelouch before preparing to eliminate him. Also, his capable of piloting a Knightmare Frame.