(covers information from several alternate timelines)
Military Assault Command Operations (commonly abbreviated as MACO) was a United Earth military organization in service on Earth during the 2150s, prior to the founding of the Federation. The MACOs (pronounced "MAY-ko") were not associated with the Starfleet. MACO weapons and technology were three years more advanced than those of Starfleet. (ENT: "Harbinger")
The military official that oversaw the MACOs was General Casey. (ENT: "The Expanse") MACO posts included Atlanta, Georgia and the Janus loop. Training posts included West Point in New York. (ENT: "The Xindi", "Hatchery", "The Council")
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 Tucker, and Kessick from the clutches of a trellium mining planet. (ENT: "The Expanse", "The Xindi")
- Rescuing Captain Archer and Commander Tucker from a Trellium mining planet (ENT: "The Xindi")
- Trying to fend off an Osaarian boarding party (ENT: "Anomaly")
- Battling on the Loque'eque homeworld (ENT: "Extinction")
- Trying to fend off a Xindi-Reptilian boarding party (ENT: "Rajiin")
- Providing escort for Enterprise officers on the Seleya (ENT: "Impulse")
- Providing escort for Enterprise officers on the Xindi-Arboreal colony (ENT: "The Shipment")
- Providing backup on a Human colony in the Expanse (ENT: "North Star")
- Guarding the prisoner Degra (ENT: "Stratagem")
- Providing combat training for Enterprise officers (ENT: "Harbinger")
- Containing a Sphere Builder test subject (ENT: "Harbinger")
- Raiding an Illyrian vessel (ENT: "Damage")
- Providing escort for Enterprise officers inside a Delphic Expanse sphere (ENT: "The Council")
- Recovering Ensign Hoshi Sato from a Reptilian vessel (ENT: "Countdown")
- Assisting in destroying the Xindi superweapon (ENT: "Zero Hour")
- Repelling a Sphere Builder boarding party (ENT: "Zero Hour")
- Accompanying Archer to a meeting with Vosk on 1944 Earth (ENT: "Storm Front, Part II")
- Escort and guard for the prisoner Arik Soong (ENT: "Borderland")
- Attempt to fend off an Augment boarding party (ENT: "Borderland")
- Attempting to take back Cold Station 12 from the Augments (ENT: "Cold Station 12")
- Escort and guard of Tellarite delegation (ENT: "Babel One")
- Boarding the Romulan drone-ship (ENT: "Babel One")
- Attempting to fend off a Klingon Augment boarding party (ENT: "Affliction")
- Ambush of kidnappers on Rigel X, just prior to the formal treaty signing that created the United Federation of Planets (ENT: "These Are the Voyages...")
|Militaries of Earth|
|Confederate States of America: Army|
|Germany: Luftwaffe • SS|
|Old Britain: Navy • Air Force|
|United States of America: Army • Navy • Air Force • Marine Corps|
|United Earth: Military Assault Command Operations|
- "The Xindi" (Season 3)
- "The Shipment"
- "North Star"
- "Chosen Realm"
- "Doctor's Orders"
- "The Forgotten"
- "The Council"
- "Zero Hour"
- "Storm Front, Part II" (Season 4)
- "Cold Station 12"
- "The Augments"
- "Babel One"
- "These Are the Voyages..."
Equipment and uniform
Their weapon seems very similar to an XM8 modular battle rifle in function and size, including the marksman variant seen in "The Expanse". The stun grenades are also very similar to "flashbang" grenades. The rifle in sniper mode also bears a strong resemblance to the Federation sniper rifle from the Star Trek: Voyager - Elite Force video games, which preceded Enterprise.
MACOs after 2161
There have been no references to any separate Earth military after the final MACO appearance in 2161. There has only been one explicit mention of a Human holding an army rank after this point in history, and the officer in question – Colonel West – was shown to be a member of Starfleet in 2293 wearing a vice admiral's rank (which would make him a lieutenant general in the army).
It seems possible that Earth's entire military structure was absorbed into the UFP Starfleet. However, it is equally as possible that MACOs continued as a separate organization from the Starfleet navy, and that Col. West held a dual commission in both organizations. The process of dissolving, absorbing, or continuing separate service organizations as a sovereign world joins the Federation is unclear; however it is known that at least one other Earth organization, UESPA, had continued as a separate agency, albeit one that was seemingly part of, or at least working closely with, the UFP Starfleet. The last known UESPA reference, on the NCC-1701-B dedication plaque (also in 2293), means it is at least possible a pre-Federation agency could survive well over a century later.
It is also possible that West had the rank of vice admiral and the "billet" (military job) of colonel. (In the British army, a general in charge of a regiment can be called the Colonel of the Regiment.) As for the continued existence of the MACOs as part of the UFP Starfleet, the British Cavalry is part of the British Army, but it still uses its older traditional names for the ranks.
"Ground forces" were mentioned several times in latter season episodes of Star Trek: Deep Space Nine, another possible passing reference to MACOs.
The novelization of The Expanse states that Captain Archer was initially uncomfortable with the notion of military personnel serving aboard Enterprise but reconciled himself to the idea, given that it seemed as if the MACOs would be beneficial to the search for the Xindi weapon. The same novelization also suggests that MACO be pronounced "Mah-co" rather than "May-co," despite the latter being the commonly used canon pronunciation.
MACOs can be seen in Star Trek Online, acting as a special forces unit within Starfleet. By playing Special Task Force missions, the player can acquire a set of MACO equipment.