(covers information from several alternate timelines)
The flag officer rank of general was used by General Casey, commanding officer of the MACOs who were assigned to the Enterprise NX-01. This rank is approximately equivalent to an Starfleet Admiral. (ENT: "The Expanse")
The rank of major was used by MACO field officers commanding larger groups of soldiers on special assignments. The insignia was a gold oak leaf on a blue shoulder patch. The oak leaf insignia appears to be carried over from the USA system insignia for major.
Major J. Hayes commanded the MACOs aboard Enterprise. Traditionally, a major is equivalent of a naval lieutenant commander. However, Starfleet had no such rank at the time. Though Hayes may have technically outranked Lieutenant Malcolm Reed, the MACO team was still subordinate to the ship's chief of security.
The sergeant insignia was three white chevrons on a blue shoulder patch.
- N. Kemper was a MACO sergeant assigned to Enterprise.
- Travis Mayweather was a MACO sergeant assigned to the ISS Enterprise.
The corporal insignia was two white chevrons on a blue shoulder patch.
Several corporals were seen assigned to Enterprise, and also posted at other Starfleet assignments.
The private insignia was a single white chevron on a blue shoulder patch.
|Enlisted personnel||Commissioned officers||Generals and flag officers|
|ENS||LT JG||LT||LT CMDR||CMDR||CAPT||FCAPT||CDORE||RADM||VADM||ADM||FADM|
|2nd LT||1st LT||CAPT||MAJ||LT COL||COL||BRIG||MAJ GEN||LT GEN||GEN||MARSHAL|
|Positions:||Crewman • Technician • Chief||YMN||TAC • SO • 3rd • 2nd • 1st • CO • DD||Portmaster • Chief of Staff • CinC|
|Services:|| Andorian • Bajoran • Cardassian • Jem'Hadar • Klingon • Romulan • SS • Terran Empire Starfleet • Terran Empire MACO •|
United Earth MACO • United Earth/Federation Starfleet • United States • Vulcan
The MACOs appear to follow the same basic rank system of Earth armies, with American insignia. The producers and writers of Star Trek: Enterprise apparently avoided the army ranks that sound naval (lieutenant, captain, etc.) to avoid confusion.