The Imperial world known as Ornsworld, also referred to as Orn’s World, is the primary Ratling homworld located in the Segmentum Obscurus.
The Gothic War
In 139.M41, Abaddon the Despoiler launched his 12th Black Crusade, also called the Gothic War. This was a vast military campaign against the Imperium of Man which would last until 160.M41. During the initial outbreak of hostilities, Ornsworld was subjected to a massive invasion by the Forces of Chaos in search of the malefic artefact known as the Eye of Night, which consisted of an embedded statue of ancient antiquity worshiped as a god by the Ratlings in the pre-Imperial era. Initially, the Chaos forces were driven back by the Imperial Guard forces, but a month later the Chaos vessels blockaded Ornsworld, launching a full-scale invasion. Millions of Ratlings died in the ensuing slaughter. Eventually, the Chaos forces found what they were looking for and departed with the Chaotic artefact.
Siege of Haupstemmler Keep
A sad chapter in the invasion of Ornsworld, occurred during the Siege of Hauptstemmler Keep, the last bastion of Ratling defiance during Abaddon’s invasion of the Ratling homeworld. A great many Chaos Sorcerers gathered to breach the walls of the mighty edifice. Combining their eldritch powers, they created a penetratrive vortex with which to smash the adamantium-clad gates. However, several of the Sorcerers mispronounced certain key words of the spell and it quickly spiralled out of control. The influx of Warp power detonated catastrophically, engulfing the besieging Chaos army and turning 3,000 of its warriors into gibbering Chaos Spawn. The explosion of Warp energy also levelled part of the north wall, much to the dismay of the Imperial Guard and Ratling defenders. The sea of mutating flesh that assailed the breach soon overran the defenders and the keep fell to Abaddon. Even now, centuries later after Abaddon left the world, rogue Chaos Spawn from the siege have to be trapped and killed by the Ratlings in summer beast hunts.
In 999.M41, Ornsworld came under attack once again from the Chaos Space Marines known as the Knights of Blood. In a cruel repetition of the horrors inflicted during the Gothic War centuries earlier, over ninety percent of its population was massacred before Imperial Guard reinforcements arrived to bolster the beleaguered planet’s Ratling defenders.