Jingo (A Discworld Novel)

A weathercock has risen from the sea of Discworld, and suddenly you can tell which way the wind is blowing. A new land has surfaced, and so have old feuds.
And as two armies march, Commander Ankh-Morpork City Watch has got just a few hours to deal with a crime so big that there's no law against it. It's called "war". He's facing unpleasant foes that are out to get him. . . that's just the people on his side.
The world's cleverest inventor and its most devious politician are on their way to the battlefield with a little package that's guaranteed to stop a battle. . . .
Discworld goes to war. . . .