From the blurb: On his 75th birthday John Perry visited his wife's grave and joined the army.
My comment: The blurb is an accurate depiction of the 1st two sentences so bonus points for a meaningful blurb that doesn't give too much of the game away.
The universe is well realised and inhabited by equally well written characters. Both are internally consistent with some disturbing concepts buried in there (see the title of the 2nd volume in the series for one of those).
A strong debut novel of military SF with some interesting twists. I'll be looking forward to the paperback of the sequel "The Ghost Brigades" later.
If you cannot see the causal relationship between "I have chocolate" and "Life is Good", you simply aren't trying hard enough. Pirates of the Burley Griffin