After a training incident that lead to the flogging of a recruit private, Theodore C. Hendrick, because of (then) Sergeant Zim's mistake he requested transfer to a combat unit, which was denied by Captain Ian Frankel, Second Battalion, Third Regiment-Training.
Eventually, Sergeant Zim found his way back into a combat command. He was promoted to Fleet Sergeant for "Blackie's Blackguards", Company D in the Third Regiment of the First Division that was commanded by Captain Blackstone. Company D was part of a "rump" battalion that consisted of two companies, C and D. Captain Blackstone and Fleet Sergeant Zim were in charge of both Company D and the rump battalion.
Fleet Sergeant Zim voluntarily dropped in position (but not rank) to command First Platoon of the Blackguards along with Temporary Third Lieutenant Juan Rico during Rico's final examination, known as the "apprentice cruise", of Officer Candidate School. It was during this time that Fleet Sergeant Zim captured a Brain Bug during Operation Royalty on Planet P. Because of his actions, Fleet Sergeant Zim was promoted to a permanent rank of First Lieutenant then brevetted (title but not the pay) to Captain.
- It is worthy to note that Zim was at Camp Arthur Currie as cadre twice. His first time was 12 years before Juan Rico's tenure when he was Corporal Zim. Captain Ian Frankel had the dubious honor of having, then Corporal Zim as an instructor when he was a recruit private attending Basic Training.
- In the OVA, Sergeant Zim is an African-American, while he was white in other media. Though in the book does not mention what race he was, it is known English was not his native tongue. In addtion, "Zim" could be the Hokkien surname "任" (Jîm). It is worthnoting that Fleet Sergeant Ho's surname could be 何 (Ho²). Together, "任何" means "any" in Chinese.
- Starship Troopers (novel)