This is another novel set in Ankh-Morpork, but also one in which Klatch, a vaguely Middle-Eastern nomadic country, is a featured player. When an island rises out of the sea in between the two countries, naturally tensions arise, leading up to an ultimately useless war, attendant with all the necessary racism and idiotic assumptions. Likewise, a JFK-like shooting leads Vimes, the commander of the Watch, to believe that somebody is doing the best they can to exacerbate the tensions... and he'd really like to find out why.
While this book may seem to be mostly about war, it is, in fact, more about the people who believe in the lies of war as glory, rather than war as a nasty thing which is not quite as nasty as the alternative. There's a firebombing of a restaurant owned by Klatchian immigrants that owes all too much to a racist movement in Britain that attacks families of Indian or Pakistani heritage. There's the riff on the superiority of "white officers" which pays homage to the mindset of Britain's empire. Of course, the officers in question are obvious morons. There's the people of Ankh-Morpork getting caught up in jingoism, with a few notable exceptions (surprisingly, one who notices the contradictions is Nobby Nobbs, supposedly not one of your brighter characters.) And, of course, there is Lord Vetinari, whose solution to the problem is as adept and understated as always.
This is classic Pratchett, with beautiful understated gags and one heck of a conscience.