Trooper Fulke was an unstable Tanith trooper, and one of the few to not strive in combat, strangely he seems to have two possible deaths in the books.
He was chosen as one of the outrider drivers escorting Bragg’s resupply detail on Caligula. When the convoy was ambushed by bandits, he visibly panicked, and to the disgust of his comrades, attempted to flee battle, before being knocked out by his gunner, Logris. The extent of his injuries is unclear, though his neck may have been broken.
In the trenches of Fortis Binary Fulke finally loses it. After his rations are attacked by vermin, Fulke lets loose with his Lasrifle, and attacks Feygor when he tries to stop him. Major Rawne is unsympathetic and orders Fulke to be executed by firing squad. It is not confirmed if the sentence is carried out, as the Tanith trenches are heavily attacked by the Shriven shortly afterwards, nor is it entirely clear whether the campaign on Caligula preceded Fortis Binary.
In in any case Fulke is assumed to be killed in action and is never mentioned again in the books.