War for the Oaks, by Emma Bull. The forerunner of the whole "urban fantasy" genre, it is set in Minneapolis. It was the first time an author mixed faeries mixed with rock n' roll, but it wouldn't be the last.
Christopher Sinclair, mechanical engineer turned priest of war, takes command of the army regiment he trained and equipped. Sent south to an allegedly easy posting, he finds himself in the way of several thousand rabid dog-men. Guns and fortifications turn back the horde, but he has other problems that cannot be solved with mere firepower: a wicked assassin; hostile clergymen; dubious allies, and worst of all his own impolitic tongue.