Rulers of the Darkness

Rulers of the Darkness by Turtledove, Harry. mass_market edition. ISBN: 9780765340757.

Magic and Destruction--On a World Scale Imagine the drama and terror of the Second World War--only the bullets are beams of magical fire, the tanks are great lumbering beasts, and fighters and bombers are dragons raining fire upon their targets. Welcome to the world of the Derlavaian War, a world which is slowly but surely being conquered, mile by bloody mile, by the forces of the Algarvian empire...forces whose most terrible battle magics are powered by the slaughter of an innocent people. In this, the fourth volume of the series which began with Into the Darkness, the war for the continent of Derlavai builds toward its crescendo as the mages of Kuusamo, aided by their former rivals from Lagoas, work desperately to create a newer form of magic that will change the course of the war. But this is really a story of ordinary people--on all sides of the conflict--forced by fate to rise to their heroic limits...or sink to the level of their darker natures.