"Fiat justitia ruat caelum (Let justice be done though the heavens fall)"
― Motto of the Discipline Corps
A Disciplinary Officer, informally known as a member of the Field Police, are specialist political officers of the Legiones Astartes who serve as enforcers of a Legion Reclusiarch's will. As members of the Discipline Corps of the Imperialis Militant they are empowered to use any means necessary to ensure the loyalty and moral purity of their fellow legionaries, including overriding or even executing a commanding officer if necessary, and so is regarded with a mixture of revulsion and admiration by the rank-and-file battle-brothers of a Space Marine Legion.
Following the defeat of Warmaster Horus and the Traitor Legions during the final epic battle of the Horus Heresy, during the Siege of Terra, much of the Imperium of Man had been left a dismal shattered thing. The resolute guardians of the Imperium, the Legiones Astartes, had been shattered by the betrayal of their erstwhile brothers, yet the Imperium was unable to mount a campaign of reciprocity against the vile Traitor Legions. The newly instilled rulers of the Imperium, the so-called High Lords of Terra, decreed that the Space Marine Legions would be allowed to rebuild and marshal their strength. Meanwhile, the forces of the Imperialis Auxilia would launch a crusade to prosecute the traitor forces. Though they were initially successful with the destruction of the various Traitor Legion home worlds, they were woefully unprepared to face the myriad threats that threatened mankind from all corners of the galaxy - both internal and external.
When darkness sought to overwhelm the shattered husk that was the Emperor's star-spanning empire, other Loyalist Space Marine Legions finally managed to reach Terra following the slow dissipation of the Ruinstorm that spanned most of the known galaxy. Once reunited with their fellow legions on sacred Terra, it would take several centuries until the Space Marine Legions were finally brought back to full strength. Once this was accomplished, the Second Great Crusade could finally begin in earnest with the newly rearmed and re-equipped Space Marine Legions at the forefront of the Imperium's conquering armies. But the process of rebuilding would take many centuries until the Legiones Astartes was brought back to full strength.
Thus, the Imperium's most brilliant fleshcrafters and gene-wrights, working in conjunction with the Selenar gene-cults of Luna and the Magos Bioligis of Mars, focused on perfecting and removing existing genetic deficiencies in that had been identified in the gene-seed of several Space Marine Legions. The Imperium was able to create a new generation of Space Marine Legions from existing gene-seed, after having many of their genetic flaws and deficiencies removed. Thus, the Second Founding would occur at the beginning of the 32nd Millennium.
By the 33rd Millennium, the stability of the gene-seed began to diminish through over-use and the increasing need for ever greater numbers of Space Marines in the field. This was a matter that only worsened as the Second Great Crusade pushed ever wider afield into the galaxy. Imperial forces could no longer be concentrated as easily as before, and attrition was taking its toll as years of near-constant battle became decades. With the advent of the crisis known as the Nova Terra Interregnum, the time of 'twin empires', when the Imperium was split in half by the secession of the entire Segmentum Pacificus by the Ur-Council of Nova Terra, the simple truth was that more Space Marines were needed and they needed to be created faster than before.
Utilising accelerated gene-culturing techniques not used since the First Great Crusade, three Space Marine Legions were created in record time, and so, the Third Founding, or 'Numroi Founding', took place in 098.M33. These few Legions were created to be massive, hosting hundreds of thousands of Legionaries within their ranks. But the shortcuts taken in their creation would have unforeseen flaws. These particular Legions came to be characterised as being battle-hardened, and particularly bloody-handed and unforgiving. During this conflict, several Space Marine Legions seceded from the Imperium and joined the Secessionist cause. Though troubling, this was not unexpected, as the High Lords of Terra were well aware of some troubling traits that had begun to manifest themselves within some of the later founding Legions, particularly a tendency to display a high degree of independence, preferring death over subservience to an authority from outside their Legion of any kind. Others were prone to physical or mental collapse in the heat of battle.
As the carnage of the Nova Terra Interregnum dragged on, both sides suffered horrendous casualties during the eight centuries-long conflict. It is now believed by Imperial scholars that the constant grinding warfare, coupled with having witnessed firsthand, atrocity and unthinkable carnage at the behest of distant and uncaring masters, caused many separate Great Companies, whole Chapters and sometimes, even entire Legions, to secede from the Imperium. These warriors were often hardened veterans who had survived against all odds and trusted only in the man next to them in the line of battle. For brothers they would fight and die and strive to see another dawn, but for great cause or Primarch, and the lies and whispers of lords and potentates alike, they had nothing but scorn. Accelerated gene-culturing techniques, coupled with accelerated psycho-indoctrination that was often utilised during that time, were often to blame for these deficiencies and breakdown in discipline.
To ensure discipline was maintained within the rank and file of the Space Marine Legions, many within the Chaplain corps advocated the use of a political officer class to help a Legion's Chaplains enforce discipline and oversee the morale of their fellow battle-brothers, instilling within them the values and beliefs of their Legion and promote the veneration or in rare cases the actual worship of the Emperor of Mankind. With the blessing of the Ecclesiarchy and the final approval of the High Lords of Terra in 535.M33, the Discipline Corps of the Imperialis Militant were created to ensure control and discipline and to improve morale of the rank-and-file Legionaries of a Space Marine Legion and to ensure proper compliance of regulations were adhered to at all times.
Disciplinary Officers are hand-picked by the Legion's Reclusiarch. These are usually battle-hardened veterans who adhere strongly to the tenets of loyalty and discipline and often display an abiding faith in the Emperor of Mankind. These individuals are considered Chaplains-in-training, are are accorded the proper respect by the rank-and-file legionaries. In battle, the Chaplains will be at the forefront of a Legion's battlelines, while Disciplinary Retributor Squads typically operate as independent five-man squads. These Disciplinary Officers serve to maintain order in the ranks, both during and away from battle, as well as curb any attempts to disregard or circumvent orders. They often interact and support attached Imperialis Auxilia units by organising stragglers, re-grouping broken units, and ensuring discipline is maintained at all times. Displaying the power of life and death, a power they are infamously quick to exercise in its extreme, they are known for carrying out summary punishments for any merely human forces who they feel lacks militancy or discipline.
They are also charged with providing overwatch of a particular unit or squad that has transgressed, but are considered redeemable, in the eyes of the Emperor. While Disciplinary Officers are authorised to help direct a Space Marine squad that has lost their sergeant during a battle, many of their fellow legionaries often hold them in contempt, seeing them as over-glorified 'nursemaids', but will nevertheless comply with their position of authority. Disciplincary Officers are also charged with assisting in the apprehension and return of those individuals or squads of recalcitrant legionaries who attempt to desert, help support the Imperial military courts of justice, and assist in collecting and transporting prisoners of war.
The Disciplinary Officers wear the twin flame-blade insignia of the 'Sanghauta' which is prominently displayed upon their right shoulder pauldron and on back banners. This icon is presumably of ancient Terran origin, and is also utilised by the Discipline Masters and Provost Corp of the Imperialis Militant. This symbol carries with it a very definite meaning; it displays clearly the power of life and death every Disciplinary Officer of a Legion has over their brothers, and are marked by the distinctive emblem of their oft-maligned Order.