MACO ranks

The rank system used by the United Earth MACO military force of 22nd century, and the Terran Empire in the mirror universe, are based on traditional army and naval ranks from Earth's past.

General
The flag officer rank of general was used by General Casey, commanding officer of the MACOs who were assigned to the. This rank is approximately equivalent to an Starfleet Admiral. 

Major
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.

In the mirror universe, Major $𝜇$ was the chief of security aboard the.

Sergeant
The sergeant insignia was three white chevrons on a blue shoulder patch.


 * N. Kemper was a MACO sergeant assigned to Enterprise.
 * $𝜇$ was a MACO sergeant assigned to the ISS Enterprise.

Corporal
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.

Private
The private insignia was a single white chevron on a blue shoulder patch.

Background information
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.

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