Solar Auxilia - Strategic Disposition of an Expeditionary Fleet/Battlegroup: The following illustrates the  strategic disposition of the Excertus Imperialis for a Macro-Command Level Expeditionary Fleet/Dedicated Battlegroup:Primary Lord Militant/Lord Solar(I) (Secondary tier by deployment type) - Individual assets of a lord militant of any kind will vary widely, but will commonly include personal flagship (capital class), various escort vessels, retainer cohorts, life guard elite, specialised irregular regiments, full general staff and analytical cadres, indentured servants and hirelings, bursary and interior trains, emissaries from various potentates and divisions of the Imperium's body politic, etc.Lord Marshal (Expansion/Battlegroup Command)Lord Castellan (Garrison/Defence Command)Lord Admiral (Primary Armada Imperialis Fleet Command)Strategic Operational Command (Tribunes General and Subordinate Staff Officers, Officio Locum Strategos, Senior Representatives of the Armourium, Artillerists, Munitoria, Officio Medicae, Lectato and Discipline Corps) - Centralised resource of strategic operations and general staff for the Expeditionary Fleet/Battlegroup, as distinct from private retainer counterparts operating as part of the lord marshal's personal retinue.Subordinate Office of the Admiralty & Fleet of the Armada Imperialis - Includes all detached vessels, stations, crews and assets of the Armada Imperialis under the purview of the lord militant, including its commensurate parallel naval strategic command (Admiral Primaris and subordinate ranks). Also, this office included any attached high-ranking members of the Astra Telepathica and Navis Nobilite.Mechanicum Assigned Detachment - Comprising the independent command structure of permanently or semi-permanently detached Mechanicum forces, and their sub-factions. (Primary) Magos Militant, Enginseer Covenant Excertus, Emissaries Mechanicum. (Secondary) Allied Taghmata, Ordo Reductor, Legio Cybernetica, and Legio Titanicus foces.Cohort and Regimental Command Structure (Simplified Overview) - The bulk of the Excertus Imperialis armed forces are made up of independently operating regiments, Militia Legions Minoris and cohort-structured "sub-armies". Each of these varies by their internal structure, size, muster and strategic use (and thereby their equipment and training) as well as their world/system of raising and/or origin. These were broadly classified and ranked in order of military power and seniority by the Principia Belicosa as follows:Cohorts and Regiments Primus(II)Cohorts and Regiments Secundus(III)Militia Legions Minoris(IV)Provender & Labour AuxiliariesPenitentiary and Punishment Cohorts and Legions MinorisDepending on their size and deployment, battlegroups and expeditionary fleets may order between a dozen and over a hundred such independent formations, potentially therefore numbering in the tens of millions of men and women under arms.Extra-Incorporate Assigned Forces - Varied and diverse operatives, agencies and irregular forces operating under the authority of the Lord Militant, but outside the usual chain of command, are notionally located in this division of authority.Agents of the Imperial Court, Agents of the Assassinorum, Plenipotentiary Representatives of the Council of Terra, (prohibited)Assigned detachments of the Legiones Astartes, Households of the Knights Questoris[Rogue Traders Minoris, Chartist Captains, Reflugators, Ordnancers Assay & Provender, Justicars Arbites and their respective staffs and cadresDeputations of the Order of Iterators, Remembrancers and Savants LogosWarden Charonate, (prohibited), (prohibited)Additional Notations:(I)A Lord Militant ranks as one of the highest authorities in the Imperium, equal to the Imperial Commanders of major worlds, and the highest officers of the Imperial Court, in effect, subordinate only to the will of the Emperor, His personal representatives and, by extension, the primarchs.(II)Primary level cohorts and regiments are the most powerful forces within the Excertus Imperialis, comprising elite formations such as the Solar Auxilia, Pioneer Regiments, Armoured Cohorts and Regiments of Renown.(III)Secondary level cohorts and regiments represent a second tier of ability and force, including many indentured forces from Compliant worlds, lightly equipped "regular" forces intended for non-critical Compliance garrisons, as well as frontline auxiliaries considered to be liable in some way, such as Feral Worlders and Abhuman regiments.(IV)Militia Legions Minoris were forces raised in extremis from subordinate local populations, and are often poorly-equipped and poorly-trained, and often are used for the purpose of planetary defence emergencies, etc.