Military Assault Command Operations

The MACOs (an acronym for Military Assault Command Operations) were a United Earth military organization in service on Earth in the 2150s, prior to the founding of the Federation. The MACOs (pronounced "MAY-ko") were not associated with the Earth Starfleet.

The military official that oversaw the MACOs was General Casey. MACO posts included Atlanta and the Janus loop. Training posts include West Point in New York.

A detachment of troops commanded by Major J. Hayes was assigned to the Enterprise (NX-01) for its mission into the Delphic Expanse in 2153. Admiral Maxwell Forrest was surprised that Captain Jonathan Archer had requested military officers aboard his ship. They saw their first action six weeks into the mission, in September, Hayes and a six-man team rescued Archer, Commander Charles Tucker, and Kessick from the clutches of a trellium mining planet.

MACOs have similar weapons, training, and tactics to the special forces of a number of member nations of United Earth (the US Navy SEALS, Delta Force, Army Rangers, Marine Force Recon, etc), and their rank insignia is similar to that of the U.S. Marine Corps.

From Memory Alpha -- the free Star Trek reference