Sachael was the Grand Master of the Deathwing of the Dark Angels Chapter when the Ork forces of The Beast invaded the Imperium. He later commanded the Battle Barge Reprisal, when he led his Chapter in battle against the Orks, after they invaded the asteroid field known as Astorias Cloud; which contained numerous Imperium mining installations. During the battle, he tried to navigate the asteroid field, to fire upon an Attack Moon within it, but was cornered by Orks ships and soon required assistance. However, when Company Master Adnachiel was ready to come to his aid, aboard the Strike Cruiser Herald of Night, Sachael suddenly told him to abort his rescue attempt. The Dark Angels had just received word that their aid was requested for a strikeforce, that was being formed on Terra to attack the world Ullanor and Adnachiel had been chosen to be a part of it. Though Adnachiel did not want to leave without aiding Sachael, the Deathwing's Master told him of the mission's importance, as Ullanor was discovered to be the origin point of The Beast's invasion force, and promised the departing Company Master, that he had no intention of dying within the asteroid field.