During the battle, the Alpha Legion was assaulted by Ultramarine forces. Alpharius (or perhaps Omegon posing as Alpharius) was reportedly happy with such a development, as it allowed him to demonstrate the superiority of his flexible, multitudinous and unexpected military strategies on the notoriously precise, methodical and perhaps even moribund Ultramarines. However, the Alpha Legion primarch was apparently taken by surprise when Guilliman departed from his own strictures and led a surprise assault by his elite units on the Alpha Legion headquarters. In the resultant personal combat between Alpharius and Guilliman, it is believed that Alpharius was killed. The Alpha Legion responded, not by breaking and fleeing as Guilliman expected, but by turning on the Ultramarine detachment and harrying them so mercilessly that by the time they had returned to the main body of the Ultramarine force their casualties were almost total. The Ultramarines were driven from the planet in the subsequent battle. Following the battle on Eskrador, the Alpha Legion fractured in order to hide from the Imperium and it is unknown what the state of the planet is the 41st Millennium.