Astra Militarum - Anatomy of an Astra Militarum Regiment: The Astra Militarum is a colossal organisation, dwarfing every other military force in the Imperium for sheer manpower, and matched only by the Imperial Navy in logistical complexity and universal significance. It has been claimed that for every star visible from the surface of Terra, there are a hundred million Imperial Guardsmen waging war on some distant world in the Emperor's name, though nobody could possibly know how many Imperial Guardsmen there truly are at any one moment, so vast are their numbers and so quickly do those numbers change. However, what is certain is that every one of these brave souls, and more besides, are required to fight and die for the Imperium in order to try to preserve it.Some have claimed that the numbers of the Imperial Guard are matched or even exceeded by the sheer number of scribes, adepts, prefects, and a bewildering array of other administrative officials in the Departmento Munitorum whose duty it is to ensure that the Imperial Guard are able to fight their countless wars. In their hands is the impossibly complex task of raising armies from a million individual worlds, each with a different culture, equipping them in an appropriate manner, and ensuring that every man and woman is fed, watered, and supplied with ammunition.What this all boils down to is the regiment. The regiment is the building block of the Astra Militarum, and the nature of each regiment defines how it is to fight, how it is to be equipped, and the manner in which it is best employed. Regiments are raised either as part of the tithe that all worlds contribute to the Imperium, or as necessary from worlds within a particular distance of a newly-opened warzone. It is a rare world in the Imperium that has not raised at least one regiment of Imperial Guard, with the overwhelming majority of those being the tithe-exempt Forge Worlds of the Adeptus Mechanicus and the Chapter homeworlds of the Adeptus Astartes, both of which produce their own particular fighting forces.Though regarded as such by many within the Departmento Munitorum, a regiment of the Imperial Guard is not a uniform mass of warriors, equal in might and utility to every other regiment. On the contrary, regiments vary immensely in size, structure, and purpose, from small, deadly, armoured regiments, to bewilderingly large regiments of siege infantry. In truth, the regiment is a difficult thing to define, but some might classify it thusly: a regiment is the operational unit of the Astra Militarum, a discrete formation of Imperial Guardsmen, all trained and equipped to operate in a single way, and all drawn from a single world and its dominant culture, the combined regiments forming the "Militarum Regimentum" -- all the regiments of that type raised from that world for the Astra Militarum in the Imperial tithe. All other factors are subject to local variation and prevailing logistical doctrine -- at times, all the fighting men and women taken from a single world at a single time have been classified as a single regiment, creating units of millions of troops, while other periods and places have attempted to define a set number of warriors or an arbitrarily calculated fighting strength to determine a regiment.Nonetheless, some elements remain consistent. At the top of every regiment in the Astra Militarum is a single commanding officer, commonly given the rank of Colonel, who serves as the frontline combat leader. Traditional expectations are that a Colonel takes to the field with his or her men, leading in person, and is often accompanied by advisors such as Imperial Navy Aeronautica Imperialis liaisons to provide air support, Adeptus Ministorum preachers, psykers, Tech-priests, and the dreaded commissars.Each regiment is typically divided into several companies, each of which is commanded by a Captain or Major. A company normally consists of several hundred warriors, and can serve well as a fighting unit in its own right, with individual companies commonly split off to achieve distinct objectives pertaining to a regiment’s overall mission. Within each company, the unit is further divided. The exact term used varies by type of company, with vehicle companies divided into squadrons, infantry operating in platoons, and artillery operating in batteries. Each platoon, squadron, or battery is typically commanded by a lieutenant, the most junior of officers, new to the service of the Imperial Guard.The most basic building block of the regiment is the squad. In an infantry regiment, the squad is the smallest operational unit, overseen by a Sergeant. In an armoured or artillery regiment, each squad is given a single vehicle or artillery piece to control, with different troopers serving as gunners, loaders, drivers, spotters, and a variety of other roles, as required by their duties.