The crew of the USS Merrimac includes the 1stBattalion 44th Star Fleet Marines. The 1/44th gives the Merrimac a superior ground force capability over most Star Fleet vessels. The Fleet Marines are specially trained and equipped for ship to ship as well as tactical ground operations. On ship the Marines augment the security staff  Force Recon squads provide needed ground intelligence information and provides a strike force in hostage situations.

On board the Merrimac the Marines augment the security staff and make up the intruder alert reaction team.  Their job is to protect the ship from boarding parties and to protect key areas of the ship such as engineering and the bridge.