Blood & Iron — Harry Turtledove

World War 1--The Great War--has ended, and an uneasy peace reigns around the world. Nowhere is it more fragile than on the continent of North America, where bitter enemies share a single landmass and two long, bloody borders. In the North, proud Canadian nationalists try to resist the colonial power of the United States. In the South, the once-mighty Confederate States have been pounded into poverty and merciless inflation. The time is right for madmen, demagogues, and terrorists. With Socialists rising to power in the U.S., and a dangerous fanatic in the Confederacy preaching a doctrine of hate, more than enough people are eager to return the world to war.