Boros

Boros is an Imperial planet in the Ultima Segmentum. No sector, subsector, system or coordinates are recorded for it, and it is distinct from Boros Prime of the Boros Gate.

In 944.M41 Boros was invaded by the Ork Empire of Charadon, the long-lived greenskin realm that had troubled the Ultima Segmentum for centuries. Chief Librarian Varro Tigurius and the Ultramarines 4th Company destroyed the invaders, a victory that halted the empire’s potentially disastrous expansion for a time. Another account places the Ultramarines forces at the Devastation of Boros under Chapter Master Marneus Calgar, with his Thunderhawk Herald IV.