As you already know, 14 million civilians from the Hive cities of Palladia (Pop ~74 Trillion) were re-located, some willingly, some less so, to Devos IV. It is well documented that the astropathic message warning those on Devos IV that the immigrants were coming arrived some eight decades after the war had finished, such are the vagaries of the warp.
Doubtless you were wondering where they came from; there were a few neuveu riche and some scions of the great houses of Palladia. But the vast majority were those whom the rulers of the Hive cities wanted moved for whatever reason. So here is a sample:
Cité Soleil, or “Sun City” is Danter Hive’s largest slum and its most dangerous. The gangs run this ghetto. Some parts are too dangerous for the Adeptus Arbities to patrol. It’s eight constituent districts are buried deep in the bowls of Danter Hive and the sun (or wind, rain or any other meteorological phenomena) has not shone on Cité Soleil since the rest of the Hive scabbed over it over 500 years ago.
A population of roughly 500,000 live in Cité Soleil, the majority in poverty. Outsiders need permission from the gangs to travel in certain areas. “Ahh, the gangs,” Arbities Inspector Lemastre Dominique said. “All sorts of crimes — rape, murder, a little of everything. Guns, stealing organs from people and running a black economy based on illegal narcotics. All controlled by the gangs.”
In Danter Hive, Law-and-order effectively collapsed following an earthquake eighteen years ago. Thousands of prisoners held in the hive’s jails escaped back into the slums. The authorities overwhelming response quickly restored the rule of law where it was demanded, however valuable resources are always in demand and perhaps they left a little too soon.
The Adeptus Arbities have a reputation for impartially enforcing the Emperor’s Laws, being extremely resistant to corruption by being largely removed from local politics and recruited from off worlders. On Palladia, there was a policy move five decades ago to increase the number of locals into the serving Arbities in order to bring more local knowledge and a better ‘feel’ for the Hives into their work.
This policy has largely fallen by the wayside but in neglected areas, like some underhive areas of less important spires of less important Hive clusters, a lack of oversight by more regularly governed Arbities has resulted in an almost feudal or hereditary local arrangement. Political immunity, a lack of independent checks and balances, constant exposure to gangsterism and ample opportunity to indulge ensured that last two decades of Adeptus Arbities presence in Danter’s underhives were infamously corrupt.
Across Palladia, Policing all levels of its Hive cities, including underhives like Cité Soleil officially falls to the Adeptus Arbities, which has received Trillions of dollars in funding and equipment from the Departmento Munitorum and the High Lords. But as number of Astra Militarium peacekeepers in the underhive declines, a greater share of the security burden falls onto the newly formed Local Police.
The Local Police has replaced the military as Danter Hive’s security force twelve years ago. Before the Adeptus Arbities officially left Danter Hive, it’s officers controlled the population through the deployment of sheer terror. Adepts executed dozens of people every month, killed children with chainswords and displayed bodies in public to frighten people into silence. And the Adeptus Arbities were still struggling to keep a lid on the cauldron of discontent in the bottom levels of the Hive. Something new was needed.
“I do the patrol, in a brick of five officers, every day to protect the streets,” Yoles Charon, a Local Police officer, told us during a patrol. “We do our job to protect the population in Danter Hive.” The Bricks are organised into cohorts of twenty bricks, each commanded by a Centurion, twenty cohorts form a brigade commanded by a Commander. The eight Brigades, all recruited from other Hives and demobbed Palladian Guardsmen, are each responsible for a specific district of Cité Soleil.
The Local Police has a reputation for excessive force, but it’s a “stronger and more respected force today,” according to the local representatives of the Holy Inquisition. The Local Police, since it formed, has focused heavily on arresting kidnappers.
When the opportunity to divest itself of nearly 15 Million citizens arises, there are second and third sons from wealthy dynasties emigrating with sufficient funds and significant retinues in order to establish new branches of their family in a new territory. But the vast majority are the lower Hive population, all of Cité Soleil and many other such places, plus a heavy handed coterie of religious mentors representing ecclesiastical sponsorship.
Whilst vast number of Palladia’s Hive dwellers would jump at the chance to start a new life somewhere where they were not breathing each other’s skin and drinking filtered condensates, clearing out whole swathes of multiple hives would take a long time and require the combined might of the Adeptus Arbities, Palladian Guard and Local Police forces to move the unwilling. And there would be many unwilling.
In the confines of the transport fleet, there is an uneasy peace as the gangs adopt a lower profile and wait to see what opportunities they will find on Devos IV.
 ie everywhere that isn’t neutral ground between gang strongholds. Public places like church precincts, mass transit nexus points, hospitals and other welfare facilities, all of which are chronically underfunded, dilapidated and barely functional (in the underhive), also serve as neutral ground for the gangs who often use these places for negotiations and prisoner exchanges and so on.
 Due to the perceived lack of legitimacy of the Adeptus Arbities in many places, the Palladian guard, sometimes as themselves, sometimes as paramilitary ‘Planetary Unity Cadres’ deployed to the underhive. Whilst they could aid in the policekeeping and temper the worst excesses of the Arbities, the Commanders of the Palladian Guard principally saw this as a warm up for any unit deploying to the Third Edethorian War. When this ended they swiftly lost interest in sending battalions to gallivant around the underhives.
 Legally, they are defensive municipal militia. They carry military weaponry and wear flak armour with grufallo hide boots and gloves. Their navy uniform is topped off with bright red head gear. Each of the eight brigades wears a different red hat to identify itself; berets, kepi’s, forage caps, side hats, Stetsons, bandanas, top hats and Phrygian caps. Of course all are replaced with the Cadian Mk8 tri-dome helmet, as worn by the Palladian Guard, during combat operations.
 It had got to the point where the lack of trust between the Adeptus Arbities and the population of Cité Soleil had come to the attention of the Hive President who, of course, would have to answer to the Planetary governor if he lost control of (part of) his Hive. Hence the need to remove the Adeptus Arbities and replace them with something different; the long term outcome would not be any different, but this would postpone it for another few years.
 16000 front line Policemen are not enough to establish the rule of law in a place like Cité Soleil. However they are the biggest, best armed gang (and still able to call on out of area resources) and can establish the rule of law in localised areas for significant periods. Their effectively unlimited resources and reinforcements mean that the criminal gangs are loathe to take them on, preferring to lay low and re-establish themselves when the Local Police move on to their next assignment.
 When the opportunity was tabled at the Planetary Governor’s cabinet meeting, like his peers, the Danter Hive President already had a readymade population of volunteers.
 These privileged few will travel in comfort and arrive well resourced. On post war Devos IV, many will fail, some spectacularly, but some will succeed beyond their own expectations and those of their sponsoring families.
 In some of the larger ships, there is literally a truce between gangs. Some smaller ships are host to one gang who rule the rest through fear and intimidation. In other places, previously harsh and unpopular gangs, outnumbered by those they oppressed, did not make it to Devos IV.
 Exactly the same as the scions of the ruling houses of Palladia, the gang lords see the possibilities and are biding their time.