Corporal Ellenbogen's exact relationship with Jake in military school is unknown, but he definitely inspired a good measure of fear in Jake, such that Jake still has nightmares about him from time to time and must be reassured by Helen that Corporal Ellenbogen is far away.

He taught Jake to shave behind the munitions hut, since Jake's father had a razor phobia. He was also missing one thumb, reason unknown.

Ellenbogen was also, for some reason, a drama instructor. Jake once wrote a song for a school musical, but Corporal Ellenbogen refused to let him perform it onstage. He was wise to do so - the song sucked. Ellenbogen was very into the works of Gilbert & Sullivan.

It is possible that Corporal Ellenbogen is the soldier who appears in a brief flashback of Jake's in the episode "Of Human Bonding" although both the man's thumbs seem to be intact. Perhaps he lost one of his thumbs later on? Assuming this is Corporal Ellenbogen, he is seen leaving an acrophobic Jake stuck clinging to the top of a rope, showing no sympathy to poor Jake as he pleads for help.