The Corillis system is a standard star system located roughly 14 lightyears to the galactic south east of Cadia and the Eye of Terror. It is entirely under the control of the Imperium of Man, and contains two inhabited planets; Corouloth and Mandsilia.
The Corillis system consists of six planets of various sizes orbiting a main sequence star approximately two times the size of the Sol, though only two of these planets provide ideal habitats for human life unaided (Mandsilia and Corouloth). The system has received attacks from Chaos forces for almost it's entire existence, though much lighter than they should have been thanks to the Cadians.
The six planets, comprising of 3 gas giants, 1 volcanic planet and two sub-tropic planets, are for the most part in flat orbit around the system's star. In order of closest distance to the star outwards, the planets are Marooth, Praeis, Mandsilia, Corouloth, Caribis and the distant Vaen.
Civilisation & History
Corillis was inhabited at roughly the same time as Cadia in early M35, humans of the same ancestry as the fortress world making their homes on the tropic planet of Mandsilia, and the more Terra-like Corouloth. These are the only two properly lived-on worlds, and are considered civilised worlds of the Imperium.
The two planets, given the nature of their strange and often interacting orbit, share very close ties. They have a mutually beneficial relationship, relying on eachother for different things, with an integrated culture. The two planets have separate planetary governments, which comprises of an Imperial Governor and a council; though the members of Corouloth's government may (and often) contain natives of Mandsilia and vice versa.
The close ties extend right down to a basic level, where inhabitants of the two planets don't see themselves as being Coroulian or Mandsilian, instead seeing themselves as 'Corillian'. Mandsilia, being a tropical temperate planet with a population of only 2.5 billion, is the farming and cultivation hub of most of the sector, whereas Corouloth, with it's population of over 15 billion, provides most of the technology and industry to the two planets.
Mandsilia and Corouloth do not share the revered status of their close cousin Cadia, and as such are not allowed a multi-specialised military force. On Corouloth, the specialisation is it's naval forces - the Corillian fleet being one of the largest in the sector, and providing a valuable contribution to Battlefleet Scarus, partaking most recently in the Ophidian Campaign. As well as the sizeable contingent of vessels of war, the Corillian takes great pride in it's Marine Corps (CMC), a force of which numbers around 2,000,000,000 personnel. Mandsilia on the other hand, provide army capability, specialising in light infantry, numbering at roughly 350,000,000. Citizens of Corillis can join either force, no matter which of the two planets they are from. Being navy and infantry oriented planets, there is little to no armoured units in the Corillian military, with the exception of the lightly armoured Chimera utilised by the Mandsilian army. Instead, the marines will be dropped onto a planet and undertake full scale frontal assaults against targets, with supporting fire via heavy orbital bombardment from naval vessels.
In order for this tactic to be effective, the Corillians rely heavily on their navy to ensure they have orbital and aerial supremacy before an attack can be landed, as without armoured support troops on the ground are vulnerable.
The army are dropped in where terrain would not permit a successful CMC assault, and are often used to scout and gather intelligence on the enemy, or launch quick and destructive assaults.
Neither army undergo training quite as long as that of the Cadians, but they do pride themselves on the wide variety of terrains and environments they can remain effective in, due to the varied nature of the planets within the Corillis system.
The system's six planets are divided into three bands, though there is little to distinguish them. Between Marooth and the gas giant Praeis, lies an asteroid field called Staris Balteus, which is used extensively for mining. Praeis, Mandsilia, Corouloth and Caribis orbit in the next band, with a huge area of open space before the outer gas giant of Vaen.
Corouloth is the only planet which has an orbital plane which is different to that of the other planets in the system. It has an angular orbit, which runs at roughly 25 degrees to the rest of the planets, the orbit almost the same distance from the system star as Mandsilia. Subsequently, twice a year the planets cross close enough that they are both visible in eachother's skies at night - and at prime passing, during the day. The gas giant Praeis, when passing every few years at the crossing point, pulls Mandsilia away from Corouloth, restoring orbital harmony. It is not understood how this system of gravitational clockword came to be, as it is such an extremely rare phenominon, and because of this it has fascinated physicists since it's discovery. Though the two planets are put back in regular orbit by Praeis, it is predicted by the Imperial Navy that the planets will one day collide, albeit in several million years.