The Royal Manticoran Marine Corps is a component of The Royal Manticoran Navy: The Official Honor Harrington Fan Association, Inc.. Members of this component tend to focus on the Marine Corps aspect of the stories. RMN ships with a sufficient number of members who are Marines may form a Marine detachment, or MarDet. They wear the uniform of the RMMC and are addressed by Marine titles.
Within the context of the Honorverse canon, Marines form an integral part of a ship's crew; they man the ship's weapons, are crucial to damage control and are used for boarding parties or to provide a quick-reaction ground force on a planet's surface. While Marines can be deployed as a garrison force, such arrangements usually last only until they are relieved by Army units.
Marines can be promoted when they have meet the "Time in Grade", the "Time in Service" and passed any necessary courses. The courses can be found at the RMMC Enlisted Training Center.
Marine Detachments come in a variety of sizes and are dependent on the size of the ship. For a Destroyer like the HMS Havoc (DD-01) a Marine Detachment of one Platoon is authorized.