Nuceria
"Violence is the last refuge of the incompetent."
- – Isaac Asimov
Nuceria WAS a planet in the Ultima Segmentum and the original homeworld of Angron. Had he landed absolutely anywhere else, the World Eaters may not have fallen to Chaos. Imagine World Eaters being recruited from Catachan. If only.
Incidentally, its name is probably based on the Roman city of Nuceria Alfaterna (modern day Nocera Inferiore). The correct pronunciation of that Nuceria is "noo-cherree-ah", but the (mis?)pronunciation of "noo-serria" has become accepted canon. (Maybe this is because the former sounds too much like diarrhea, although given its association with Angron that could possibly be fitting.)
History: Why Nuceria was such a Shithole (Vol. I)[edit]
Nuceria was politically divided into multiple petty city-states and alliances, which constantly contested against each other for dominance. Within the city-states, various noble houses would constantly contest against each other for dominance. As you can imagine, this resulted in a poorly administered little crap hole, even by the relatively low standards of the Age of Strife. To keep the populace from revolting, the noble families used archaeotech known as the Butcher's Nails on slaves. The Nails dulled all other sensations in life and rewarded acts of aggression, turning the slaves into psychotic gladiators who would kill each other without a second thought. This in turn kept the populace distracted from how crappy their planet was.
Onto this shithole of a planet Angron was flung by the Chaos Gods, thanks to the world's worst shittiest mother/plot point. After killing some Eldar trying to stop his ascension, Angron was captured by the city-state of Desh'ea and made a gladiator-slave. Now, Angron, being a Primarch and all, didn't take that shit meekly and managed to rally the gladiators into a rebel army that laid waste to every city they came across. Unfortunately, they were simply not numerous enough to prevail (because Angron wasn't big on conquest and recruiting instead of killing everyone) and were eventually driven into a mountain range when the petty nobles realized they'd need to act like grown-ups for a moment and pool their resources to put a stop to the rebellion. Angron didn't care too much, he and his men were ready to die and awaited the Desh'eans to come and kill them (instead of using guerilla tactics to literally rip apart the enemy armies). It was then that the Emperor of Mankind came to Nuceria and found his lost son, offering him the command of the XII Legion Astartes, the War Hounds. Angron... told him to screw off, saying he would die with his brother and sister rebels. He went as far as killing one of the Adeptus Custodes accompanying the Emperor when he insisted, forcing him to retreat. Soon, the Desh'eans came, and Angron lead the charge... only to be teleported onto the Adamant Resolve, flagship of the XII Legion. The Desh'eans thanked the Emperor for putting down the Gladiator-King's Rebellion, wiped out the rebels, and promptly became compliant. However, instead of making Nuceria the War Hounds homeworld, the planet was essentially forgotten as a backwater. As long as it paid the Imperial Tithe, the Imperium of Man essentially ignored Nuceria.
Well, a century or two later, Angron returned to Nuceria. His brother Lorgar, Primarch of the Word Bearers, was forming a massive Warpstorm to cut off Ultramar from the Imperium as part of the Horus Heresy. Angron wasn't too thrilled about going back to Nuceria, as he had felt cheated of the death he felt he had earned, but Lorgar soothed him with the chance of learning more about the Butcher's Nails and maybe find a way to neutralize them. This lasted for the ten seconds it was needed for Angron to learn that the Desh'eans claimed he fled from the final battle that resulted in the defeat of his rebellion. Angron was understandably vexed and ordered the World Eaters and the Word Bearers to wipe out every living thing on the planet with extreme prejudice. By the eighth day, the Ultramarines, fresh from the battle of Calth, came calling. While Roboute Guilliman fought Lorgar, Angron intervened. But when Guilliman shattered the skull of one of Angron's fallen comrades, Angron went into a rage, and Lorgar used that rage, along with the suffering they had caused Ultramar, to turn Angron into a Daemon Prince of Khorne. Angron then proceeded to kill the last of the World Eaters Librarians, who had tried to kill Lorgar in a final attempt to keep their Primarch from falling, and forced the Ultramarines to retreat. Nuceria was left a dead world, as forgotten in death as it had been in life, until it was later completely destroyed during the Lion's campaign of blowing up traitor home worlds.
All in all, Nuceria holds the honor of being the one primarch homeworld that no one had even the slightest good thing to say about. Even total shitholes like Barbarus and Nostramo at least held some sentimental value to some of the legionnaires who grew up there, but there WERE no Astartes from Nuceria. Only Angron, and his experience there was so spectacularly awful and played such a large part in ruining him that even the World Eaters regarded Nuceria as "worthless".