For a while now, it's been a growing idea that all my 40k forces come from the same planet somewhere in the 40k galaxy. It started on the FTW post about unifying your armies and has evolved from there over the past couple of weeks. Anyway... here it goes...
History of Manutia
During the Great Crusade, Manutia was brought to Compliance by the [IMPERIAL RECORDS DELETED] legion, designated [IMPERIAL RECORDS DELETED]. They faced heavy resistance from Ork tribes on the planet, along with a brief campaign with Chaos worshipping Cultists on the planet.
Imperial Guard regiments became stationed there to recruit loyal followers and over this time, Manutian regiments have grown substantially and are expert City fighting units. During the Heresy, the Imperial Guard stationed there remained loyal to the Emperor and fought off a resurgance of the Cultists and Chaos Worshippers previously found on the planet.
Current 40k Timeline
Necrons tombs have awoken deep inside the planet causing anyone dewlling outside the Hive Cities to either retreat into the relative safety of the Hive Cities or face harvesting. Strange artefacts and structures have appeared in the Wastelands and the Manutians dare not travel too close to them - all scouting parties sent have failed to return. There has even been heretical talk amongst Manutians of a vengeful God appearing from beneath the planet. No visual confirmation has been made of this "Night God", as no survivors have returned from exploratory missions.
More and more Orks have begun to appear on the planet and nearby over-run planets, flocking to the banner of Waaaaagh Nobrot, looking to overthrow the primary planet in the Manutia cluster and use the Imperial Forges and technology to expand. These Orks roam the wastelands on the outskirts of the Hive Cities, launching constant raids to try and pierce the Defenses of the Manutian Imperial Guard.
Due to the vast underlying element of Chaos that has lingered from the past 10,000 years there are umpteen followers fo Chaos still hiding in the shadows of the Hive Cities and in the wilderness. These form resurgencies from time to time and result in unstable Warp storms and Daemons poring forth in an attempt to over throw the world. Notably the followers of Khorne, but battles with forces of Tzeentch and Slaaneshi Daemons have been ever increasing.
The world is slowly being over run and Imperial forces are dwindling. Not only from Necrons, Orks and Daemons, but also being a large Industrial planet, it is often used as a Waypoint by allies or a raid point by enemies - large amounts of Chaos Space Marines, loyalist Imperial forces and Eldar have come across the planet in recent times and the already knife-edged balance on Manutia is struggling to hold.
Most recently, an Abhuman race known as The Brotherhood of the Forge has helped the Manutians after recieving a distress call and an alliance has been forged. The Brotherhood and Manutians regularly take to the battlefield together and utilise one another's technology to combat a greater foe. There is still not been a clear explanation why the Brotherhood have appeared, nor their motives for helping the Imperium. Some whispers on Manutia say that they are a long forgotten, once mighty race of Warriors who are now resolved to piracy and a nomadic life amongst the stars.
Who knows what lies in Manutia's future, there are increasing rumours of a Chaos Crusade taking over nearby planets and systems, and the once loyal allies of the Imperium seem to become more Heretical by the day. For now, the planet holds... just.