The Imperial Marine Forces

His Majesty's Imperial Marine Forces serve as the primary space-based infantry force for The Imperial Theian Military. While, The Imperial Army contributes the bulk of troops and materiel to the Empire's ongoing land campaigns, the Imperial Marines also contribute as an elite element in many Sector Commands.

Nevertheless, the Imperial Marine Forces' primary mission remains in space, with a detachment aboard every vessel of The Imperial Navy. Larger warships may even host battalion sized units, employing them in both boarding actions and as onboard security.

The Marine's command structure differs in some respects to the Army, as Marine doctrine permits far more independence to its field commanders and advocates for a more decentralised structure, owing to its more scattered deployment posture. Marine Headquarters is based on Imperial Centre, however has small forward detachments at Bastion, Tarus Point, and Yaved Prime. Marine Forces are led by the Commandant who sits on Imperial High Command, always a High General (M) ex officio, and his deputy, the Vice-Commandant who is usually a General (M). The current Commandant, Imperial Marine Forces, is High General (M) David Roberts, HC, MSE, GFGIOM, CRM, GCIOB, GCOV, ICH.

Finally, the Imperial Marine Forces also carry the special, and unique responsibility of forming the Honour Company of His Majesty's Imperial Marine Forces, a special detachment of Marine Headquarters that is responsible for the security of the Prime Minister of the Theian Assembly and their staff.

The standard organisation of a Marine Legion is identical to those of The Imperial Army. Marine Legions are always commanded by at minimum a General (M), who in some cases will be promoted to High General (M) as a reward for victory, and/or for an expanded responsibility in a campaign (command of a Task Force, or reinforced Legion, for example). A Legion of 100,000 men will contain five, roughly 20,000 man Divisions, each usually commanded by a Major General (M). Each Division will then be further divided into three, roughly 6,600 man Brigades commanded by a Vice-General (M). Brigades can also be designated as Garrisons if permanently stationed on a certain planet for an extended period, however this is a more common occurrence with Army Brigades, owing to the more mobile nature of the Marine Forces. Each Brigade/Garrison will then further subdivide into three, roughly 2,200 man Regiments commanded by a Colonel (M). Each Regiment will then further subdivide into two Battalions of 1000 men, commanded by a Vice-Colonel (M). These Battalions will be made up of 200 man Companies, each commanded by a Captain (M), with each company being subdivided into Sections of usually 50 men, or at the discretion of the Company Commander. Sections are commanded by a Lieutenant (M) or Vice Lieutenant (M).