Odaenathus was the Chapter Master of the Ultramarines, when the Ork forces of The Beast invaded the Imperium. Aboard the Battle Barge Caracalla, he led his Chapter's fleet against one of The Beast's Attack Moons, when it appeared above the Imperium world Tarentus. Once Ullanor, was determined to be where The Beast's forces originated from, Odaenathus led the Ultramarines as part of the Imperium's strike force sent to invade the world, in order to kill the Warboss. The Chapter Master would take part in attacking the Orks' capital Gorkogrod and was later part of the combined Space Marine force that invaded the Warboss' personal Gargant; where they confronted The Beast. However, the incredibly powerful Warboss easily killed the Chapter Master, with a single blow of his fists and marked Odaenathus, as the first Space Marine to personally die at his hands.