The little country of Borogravia has been at war for as long as anyone
can remember, often with next-door neighbor Zlobenia, but generally with
anyone who’s handy. And the leading nations of the Discworld have paid little
attention, for Borogravia and its neighbors are far-off, backwards, and
dull. And then Nuggan, the god worshipped by the Borogravians, decrees
that the line of semaphore towers built by Ankh-Morpork on the border
between Borogravia and Zlobenia are an Abomination Unto Nuggan–and they
are torn down.

Meanwhile, young Polly Perks, the daughter of a prosperous innkeeper,
cuts off her hair, dresses as a man, and runs off to join the Borogravian
army. As usual, she’s following a man–her brother Paul. If Paul comes
home from the wars, he’ll inherit the inn, and Polly can go on running it
as she has been for her father. But it’s an Abomination Unto Nuggan for
a woman to own property, so if Paul dies in battle the inn will pass to a
distant cousin.

And so the next day we find Private Oliver “Ozzer” Perks marching off to
war behind one of God’s own noncoms, Sergeant Jackrum, with a squad of
other raw recruits.

You might think you’ve heard this story. You might think you can guess
what’s going to happen. You’re sorely mistaken, I feel sure.

This is vintage Pratchett, not his best but much better than his worst,
and I spent a quite pleasant week of evenings reading it to Jane.
Recommended.