Mercatorius System

The Mercatorius System is a nominally Imperium-controlled system in the Imperium Nihilus in the Galactic North-East. The system was the site of the Mercatorius Crusade, in which forces both Chaos and Xenos aligned attacked in pursuit of the system's stragetic imporance and abundance of promethium.

The system is constituted by two main planets, Mercatorius Prime, Novus Mercatorius, and one gas giant, Calgacus, around which two small moons orbit; Veniconia and Taexalus.

History
The Mercatorius System has long been an Imperial stronghold, gaining its name from its growth as a stop-off for trade ships, rogue traders, and ships from the Adeptus Munitorum heading from the Ultima Segmentum towards Terra. The abundance of both Promethium and temperate agricultural land in the system led the original capital planet, Mercatorius Prime, to grow to a population peaking at 15 billion citizens. These citizens had lived alongside ancient ruins from times long past, incorporating these ruins' art into their own culture and identity, later believing them to be relics of the Emperor. The planet was happily annexed during the Great Crusade, growing increasingly prosperous after its incorporation, developing both its own hive city of Varachia and several mechanicus complexes.

In 387.M41 the system was attacked by a force of Orks under the leadership of 'Bonapa da Great' in the Primus Ruining, which caused immense damage to the environment of Mercatorius Prime, particularly during the closing stages of the war where the Imperium increasingly relied upon orbital bombardments. The result of this conflict left the planet devastated, with Mercatorius Prime's main Hive City Varachia seeing its population drop from 6 billion to 900 million. This left swathes of the city uninhabited and victim to a significant growth in crime, with the wastelands outside of the city becoming increasingly militarised by Astra Militarum forces lest the Ork menace see a resurgeance.

The aftermath of the Primus ruining saw a dramatic growth on the planet of Novus Mercatorius and its development into the de facto capital planet of the system. The former agri-world grew increasingly prosperous as wealth, people, and resources previously situated on Mercatorius Prime were moved to this new destination. Notably too, many of the poorer castes of Mercatorius Prime were unable or unwilling to leave, allowing for Novus Mercatorius' capital hive city, Assur, to grow rapidly into a wealthy metropolis.

Over the following centuries, the growing inequality between the two planets grew, with the system's governors growing increasingly heavy handed in their governance of Novus Mercatorius. The vast ruins of Varachia were nigh ungovernable, with swathes of the city being treated as hostile and open to infrequent Imperial military operations to restore peace and order.

As the Cicatrix Maledictum tore the galaxy in two, the Mercatorum System found itself dangerously close to the powers of the warp, with it being cut off and part of the Imperium Nihilus. The planet's strategic importance increased, though, with the system being situated near a rift-corridor across the warp. This had a two-fold effect for the system. Firstly, the system began to see an increased number of heretical utterings and bodily mutations as the powers of the warp increasingly affected the population. Secondly, as the system destabilised and found itself of increasing military importance, its planets saw dramatic increases in the number of Imperial forces stationed on its planets.

The Gracchian Uprising
In 114.M42, a serious revolt occurred on the planet of Mercatorius Prime. Growing both increasingly dissatisfied at the quality of life on the planet as well as increasingly concerned about the effects of the Cicatrix Maledictum, large numbers of imperial citizens began to join the planet's gangs and cults. One of these gangs, the Maledictors, assembled forces numbering close to a million and found themselves in control of almost half of Varachia's ruins as they absorbed the territories of other gangs. While the gang had initially been open to a limited degree of co-operation, its leader Gaio Graccho found himself increasingly dissatisfied with the Imperium and corrupted by the powers of Chaos.

The uprising began with a sudden all-out attack on the Imperium controlled parts of the city. Imperial forces found themselves fighting both on the front lines against the legions of Maledictors and also cells of infiltrators amongst their own ranks. Fighting quickly moved beyond the grounds of the city as Graccho's gang members managed to storm facilities belonging to the Adeptus Munitorum, increasing the gang's power over the planet's vast expanses.

Graccho's forces were not alone, however. While Graccho had increasingly swayed towards the powers of Chaos, some amongst his legions had interpreted his word in relation to a 'four armed emperor'. What is more, this new cult sought to portray itself as more benign that Graccho's gangs, even gaining some power over the planet of Novus Mercatorum. As the uprising broke out, some members of Graccho's uprising broke off and formed their own cult of the Four-Armed Emperor.

The Invasion of Mercatorius
With the Imperium destabilised in the system, numerous nearby warbands and forces descended upon the strategically important system. From the warp appeared the armies of Chaos, seeking to support Graccho's uprising and incorporate the system into their cursed domain. From the galactic east, Xenos forces descended upon the system, intrigued both by the system's military value and the ruins which pre-dated human colonisation. These forces attacked the wealthy outer planets of the system, stretching the Imperium's forces between the revolutionary

As the system slipped further from the Imperium's hands, the system's governor Kalon Marcus requested that there be a crusade to liberate the system's citizens from the malevolent forces which threatened him. The Imperium responded in 116.M42, beginning the Mercatorus Crusade and seeking to resore the system to peaceful imperial rule.