An author who takes the microphone personally is making a claim about authority. Afghanistan Sniper is narrated by Ted Shirley, which means the account reaches you in the voice that lived it, with whatever hesitations and emphases that brings with it.
Our catalogue files the work under biographies and memoirs alongside classics and heritage, and the subject sets the register: military service, a specific theatre, and the specialised, solitary discipline named in the title. Writing of this kind stands or falls on candour rather than on style, and the author-read format tends to keep it honest.