Created by House Xianthellipse, the Fourth Wave of House Military was the first wave of soldiers to be spliced with the genetic material of lesser species — including humans. They were seen as mongrels by most of the Great Houses. The Fourth Wave was created in the 17th year of the War in Heaven.
The Fourth Wave were notoriously undisciplined and eccentric compared to other waves, even having sexual tendencies. (PROSE: The Book of the War) Fourth Wave troops could see three or four ultraviolet wavelenghts. (PROSE: The Brakespeare Voyage)
Robert Scarratt was known as the "golden success story of the Fourth Wave"; (PROSE: The Brakespeare Voyage) other great soldiers of this wave included Milkin, Vonsolador, the Buckaroo, Reaver, Razorette, and the Void. (PROSE: The Short Briefing Sergeant's Tale)
A group of Fourth Wave troops — which included the Conquistador — were once given a briefing by a sergeant-instructor from a previous wave who told them that the Enemy were tardigrades. (PROSE: The Short Briefing Sergeant's Tale)