Condemned Citadels

Throughout the Novayan East Indies and its conquered/colonized predecessor the Aegialean Empire, there existed a number of citadels that were once vibrant, prosperous citadels functioning as either cities or even economic hubs. During the early days of the Aegialean Empire, these citadels fell prey to the imperial conquests. Many a horrific, bloody battle in ages past had wiped out the inhabitants of most citadels, with the surviving few citadels yielding to imperial might; the inhabitants of most of the ruined citadels were placed to rest in catacombs deep underground. However, the corpses' sleep was uneasy and with the building of imperial prisons, cities, castles. temples and even gladiatorial arenas on top of the ruins the corpses would reawaken as hungry, furious undead which desire only to eat living flesh. As a result, the catacombs were sealed with huge doors and magical runes to keep them from overrunning the imperial inhabitants.
By the time the Novayan East Indies was established, it organized armed security and containment operations meant to keep anyone out of the condemned citadels as well as keep the so-called "catacomb dwellers" in from breaching outside.
==Citadel containment measures==
After the Aegialean Empire fell to otherworlder expeditionary forces commanded by Admiral Konstantin von Aegialeus, the Novayan East Indies learned of the existence of these citadels and, after several manned and later fairy-manned exploratory missions, forcibly ejected the inhabitants of a select number of cities, castles, temples and prisons that were built on top of the ruined citadels. Additional exploratory missions sent to scout the cave networks, sewers and tunnels located above them and below the catacombs discovered several underground rivers and tunnels leading down into the catacombs, only stopping short by a number of large rocks blocking the ways.
Only after the next several exploratory missions saw the undead breaching upward into the tunnels, sewers, underground rivers/streams and cave networks did the Novayan East Indian military commenced a massive operation to clear them out, followed by the passages being reduced to rubble with powerful explosives and every cities, castles, temples and prisons built on top of the ruined citadels evacuated of all its inhabitants; the few that had been overran were firebombed and cleared of the undead before the sewers, cave networks, tunnels and underwater streams/rivers were blocked, the gatehouses and hidden gates were blocked off with mechanically-operated hydraulic doors, drawbridges and thaumaturgical runes to keep the undead from ever escaping into the wilderness.
As part of the necessary containment measures, a series of Theodosian Walls-like structures were built around each condemned citadel; each Theodosian Wall-like great wall would have deep, wide moats and canals placed between them and the contained citadel. Meanwhile, studded bastions, soaring fortresses, closed gatehouse forts, staged killing fields, deep defense architectures and sometimes strategic exclaves (consisting of one or multiple secure bunker, fortress, pillbox and stronghold structures/complexes) were built to ensure that such would inflict murderous casualties on the catacomb dwellers. Lastly, the walls weren't sloped and simply straight to prevent the catacomb dwellers from ever climbing them, and gun emplacements and weapons batteries were mounted to provide additional firepower.
In the likely scenario such containment measures weren't economically unfeasible and/or the catacomb dwellers had not breached the surface, troops were sent to patrol the outside perimeters, exteriors hallways, corridors and passageways for any intruders who were interested in exploring the condemned citadels. The catacombs were sealed with thau/mechanically-operated hydraulic doors, drawbridges, bridges and gates and thaumaturgical runes, and CCTV surveillance/security cameras were installed by fairy troops in the passages (if there is one or more) leading to and from the catacombs, as well as the passage towards the entrance to the catacombs proper. Should it be necessary, a large, deep and wide ravine would be built within the passages and between the thaumechanically-operated gates and thaumaturgical runes to establish drawbridges and/or bridges that can be raised/lowered to prevent the catacomb dwellers from crossing them; said mechanically-operated drawbridges and/or bridges also have thaumaturgical runes that would function as fail-safe mechanisms that cannot be operated until either the catacomb dwellers were purged or hydraulic engineers and thaumaturges reclosed and relocked the gates.
If possible, a number of fairy outposts were built within the walls to keep watch on the catacomb entrances and the passages. These outposts were built within the walls, with vision slits allowing the fairies to look to see for any activities from the catacomb dwellers. To ensure that the catacomb dwellers do not know of the fairy outposts and its inhabitants, a number of fairy-made paratechs were utilized to mask the fairies' smell and must be checked every one or three hours.
===Breach response measures===
Should there be a sort of sabotage that caused the mechanical gates/doors to open and the thaumaturgical runes deactivated, the hydraulic drawbridges and/or bridges would activate their fail-safe mechanisms which cause the drawbridges to be raised and bridges to be lowered, preventing the catacomb dwellers from ever leaving; to ensure that hostile forces won't force them to be lowered and raised respectively without the proper codes and thaumic signatures, the drawbridges and bridges were rigged to detonate, preventing a catastrophe that would overrun the rest of the citadel, and the hydraulics and chain that operate the drawbridges and bridges automatically blown up to prevent enemy forces from ever using them. In the case they were unable to detonate, the passages were rigged with explosives to ensure that the paths were blocked.
In the event containment has been breached, the Novayan East Indian military would deploy air units to commence ground suppression fire missions. Helicopters, dropships, witches, dragons and even combat aerospacecraft were utilized to pour firepower into the surfacing catacomb dwellers. Ground troops were equipped with assault rifles, submachine guns, shotguns, machine guns, rocket-propelled grenade launchers, missile launchers, flamethrowers, grenade launchers, miniguns and chemical throwers were sent to wither the undead horde; such guns were equipped with explosive and incendiary munitions to help reduce the undead number. Should the clearing operations be taking place at cities and castles built on top of the citadels, additional air units were deployed for transportation and ground suppression fire missions.
Should the ground forces were being overwhelmed and ground suppression fire missions not withering the undead numbers, the military would order a hasty yet orderly withdrawal while additional air units and thaumaturges were deployed to help in the operations until the undead had been significantly reduced in numbers. If that even fails, then the Novayan East Indian military would order an operational withdrawal - the use of every air assets to cover the military's retreat, followed by a massed artillery and aerial bombardments and heavy firebombing missions that would render the undead hordes completely reduced. If only necessary, nuclear weapons, thaumaturgical weapons and eigenweapons such as the Null Divider were only to be used as last resort options.
==Armanya canon==
In the Armanya canon, the Condemned Citadels
==Sovereign Justice canon==