Planetary Defence Force - History: During the era of the Great Crusade, it fell to the Imperialis Militia to secure and to hold those worlds brought to Imperial Compliance by the Crusade's Expeditionary Fleets. Part of the vast, sprawling body of the Imperium's military and its support structure, known collectively as the Excertus Imperialis, these regiments formed what was in effect the lowest and most common run of the wider Imperial Army, or the Imperialis Auxilia as it was more precisely known. Once a world was declared Compliant and under the full control of an appointed and independent Imperial Commander, part of that Commander's principal duty was the raising of an Imperialis Militia to protect their domain and sustain their control.It was the duty of this militia to act in no small part as the enforcers of the Imperial Truth if needed, and its protectors should the Iterators and cadres of administrators of all stripes who were left behind to oversee the long transition to full concordance become threatened or meet resistance. When the Crusade hosts departed, such worlds stood alone once more. Should rebellion ignite, the world's own militia were to crush it. Should xenos raiders or outcasts attack from without, the world's own militia were to hold until help arrived. The Imperialis Militia were therefore the first, and in many cases, the only bulwark against recidivism and disorder, and its forces, whether they were raised as conscripts from a hive city's teeming masses, the yeomancy of a feudal order or tribal levies, stood guard as watchmen against the return of Old Night.The Imperialis Militia was not a coherent, galaxy-spanning organisation by any means, and, except in times of great emergency, was not subject to the chains of command of the Imperial Army. Rather, each was a colonial defence force raised from a planet's own populace and its commander-in-chief was the Imperial Commander of the world it defended. Some were ancient martial classes with their roots in the Age of Strife, while others were irregular levies activated only in direst need, and in most cases the template of command structure and hierarchy imposed by the Imperium's Principia Militaris was adhered to only in its generality. The standards of equipment and pattern of accoutrement of individual Imperialis Militia regiments were just as varied. Some wore gaudy dress uniforms or burnished plasmesh chainmail, others furs and hides, while some few might be clad in advanced armour such as local pattern semi-powered Carapace Armour. Each militia's kit was dictated by the culture, environment and technological base of their homeworld, and so also was the diversity of their weapons, within a minimum standard issued them from the Principia Militaris Command.In theory at least, Imperialis Militia armies were irregular in nature, each member first and foremost a subject of their world only called to arms in times of emergency, but many worlds with large populations required a standing army simply to maintain civil order as well as deal with any outside threat. In practice, many Imperialis Miliita forces consisted of a core of professional soldiery, supplemented by an influx of men and women called upon to serve a period under arms as needed, after which they returned to their previous lives. The core of professional commissioned and non-commissioned officers of the Imperialis Militia were usually career soldiers, even on worlds without a strongly martial culture.In many cases, these were often older Imperial Army veterans retired from the Great Crusade into a position where their skills and experience might still serve the Imperium. The darker side of this coin was the indenture of prisoners, recidivists and thousands considered to be members of Abhumanity mutations below the standard of the accepted human norm, but not so debased as to warrant immediate extermination. These forces often served the Imperialis Militia entirely unwillingly, their control guaranteed by cadres of veteran Discipline Masters, and the ruthless application of lethal sanction and chemical inducement where needed.