Fortis Primaris

Fortis Primaris is a medium-sized Death World located within the Calixis Sector of the Segmentum Obscurus that serves as the homeworld for the Hollow Wardens Space Marine Chapter. Fortis Primaris is one of the most heavily polluted inhabitable planets in the Milky Way Galaxy. The massive obsidian fortress-monastery and city of Adamant Rook serves as the only safehaven from the extremely toxic and dangerous wilds of the planet. Once a Feral Planet of vast oceans and untamed jungles inhabited by a race of Xenos Insectoids, the planet is now but a shadow of its former beauty. Fortis Primaris is located very close to a small, but greatly volatile Warp Rift known as "the Eternal Hunger."

Pre-Imperium Inhabitance
Fortis Primaris was originally home to a Chaos-worshipping Insectoid race. This race lived in scattered tribes within the vicious jungles of the planet. These tribes fought constantly in small skirmishes over territorial concerns and other such tribulations. These conditions, as well as the devotion to the Chaos Gods the Insectoid bore, provoked the opening of the Warp Rift that resides nearby Fortis Primaris in the modern day. Despite such, the Insectoid race lived almost untouched by the Imperium of Man.

The War of the Beast (544.M32)
As the great green tide of M32 swept across the Imperium, so did it clash against worlds not under the Emperor's authority. Such was the case with Fortis Primaris. The planet fell victim to a massive Ork Waaagh!. The Orks ravaged Fortis Primaris, establishing a domain in their wake. The native Insectoid race was driven to extinction from excessive slaughtering by Orks. The Ork domain established on this planet became very large very quickly. The planet's resource-rich environment and suitible living conditions proved an immense boon for the Xenos.