The First World War seems to have been too beastly for literature, or perhaps simply too efficient at killing the people who might have written novels about it. Other than the Poets (or to quote Blackadder, the "endless, bloody, poetry") and which my not having read is rapidly becoming a mortal embarrassment, this seems to be the only significant work of literature produced by a combatant about the front line. Frederic Manning certainly wasn't your common-or-garden Tommy — he was a litterateur, an Australian, probably gay, and in his late thirties when he enlisted — but is a monument to the men who found themselves, through no fault of their own, entrenched in the Somme. What makes it live and breathe is the ventriloquism — the brilliantly rendered voices of a Britain where regional accents and vocab were yet unmuddied by mass media. I learnt for "crazy", and for a cobbler, and I was glad to see that "cunt-struck" has over a century of pedigree. The swearing is as fluent as can be. Very few writers can render accents convincingly in prose, and Manning is one of them. He was with the Shropshires (or "Westshires" in the novel), where I'm from, and some of the voices here reminded me of the codgers they brought into my primary school in the 80's to tell us first-hand what a terrific disaster the whole thing was for everyone involved.

Good review but I have to chafe at the statement All Quiet at the Western Front is the only significant WW1 novel by a first hand witness. Off the top of my head I can think of In Parenthesis by David Jones, Fear by Gabriel Chevalier, and Goodbye to All That by Robert Graves as all fairly major literary works by front line veterans. I think a big issue is a lot of WW1 literature is overshadowed by the constant demand for WW2 stuff. I will however keep an eye out for this, it sounds very interesting.
Ha! I’ve actually read the first two you mention and they’re both excellent! I want reread In Parenthesis at some point. Yeah I didn’t think for very long when I wrote that. I still think there’s a notable scarcity of WWI novels though.
On a pure numbers basis its plausible, but I do think a part of the issue is availability and popularity (for instance, I can't think of any Italian or Russian WW1 novels outside of a short story by Teffi, but surely they must exist somewhere).