Shortly after the Horus Heresy, the Emperor forsaw the need for warriors to defend his people from within. Gathering the most trusted of his advisors, he sent them on a quest the gather "men of character, skill, and determination" who would form the basis of his new force. His Inquisition grew steadily, with each Inquisitor finding and tutoring their own retinues of protégés who then went on to become fully fledged Inquisitors, but soon Lenehen was attacked again by a new type of chemical weapons, fired by Lenehen's oldest enemy- the Babylonians. Billions were killed by this terrifying new strain, and even the Emperor himself was afflicted- being interned to the Golden Throne to maintain what little life he had left.
But this attack only strengthened the resolve of the Inquisition, and made the High Lords of Terra realise the need for such an organisation, and granted it unlimited powers over the Imperium of Lenehen, as long as they kept their people safe and their Imperium together. And such, The Imperial Inquisition was born.
The Inquisition is split into two types of Ordos, the Ordos Majoris who have a larger role in the Inquisition and the Ordos Minoris who are smaller but more specialised for their task. The three main Ordo Majoris are:
- The Ordo Hereticus (The Threat Within)- This Ordos investigates allegations of Heresy within the Imperium of Lenehen, as well as policing the Ecclesiarchy. The Ordo Hereticus is the most feared of all the Ordos, as to be found guilty of Heresy (Or to be found sufficiently lacking in faith) is punishable by death. News of the deployment of an Inquisitor in a region is often followed by a monumental drop in crime, as every citizen obeys the Lex Imperialis to the letter, as only the foolish would give a Hereticus Inquisitor reason to investigate them and their family. The Ordo's military arm is the Adeptus Sororitas.
- The Ordo Xenos (The Threat Without)- This Ordos investigates and eliminates foreign influence on the Imperium. The second most feared of the Ordos, The Ordo Xenos is capable of sentancing entire cities to death if they deem them too badly tainted by foreign influence. This Ordos is the reason why the Lenehenese are usually hostile to any foreigners, as the crime for associating, dealing arms or technology with, or hiding a Xeno is death. However, since the Ordo only deals with Lenehenese matters, it is rare to see one out of the country. The Ordo's military arm is the Deathwatch, but can requisition entire armies of Imperial Guard or Astartes if needed.
- The Ordo Malleus (The Threat Beyond)- This Ordos investigates rival nations abroad, the most common being The Eternal Empire of New Babylonia. Rarely seen by the average Lenehenese citizen, most people are oblivious to their existance. Their job is to hunt down and destroy any individuals, groups or ideas which may be harmful to the safety of Lenehen. The Ordo's military arm is the Adeptus Astartes chapter of the Grey Knights.
- The Ordo Sepulturum- Created to conceal and stop the spread of the Infected during Z-day.
- The Ordo Sicaris- Created to police the Inquisition, as people with the power of life and death over millions of people is bound to lead to corruption. Recruited from the most loyal, able and puritanical members of the Inquisition, they are rightly feared.