Fortune's Stroke — Eric Flint; David Drake

EVIL FROM BEYOND TIME RULES THE GREATEST EMPIRE ON EARTH!

Link, the supercomputer from a future that should not exist, has used terror and gunpowder weapons to forge the Malwa Empire on the Indian subcontinent. No power on Earth in the 6th century could stand against Link's evil.

Aide, a human soul embodied in a jewel, has come back to halt evil's progress. Aide has no power but that of truth; but only truth could move the greatest general of the age, Belisarius. With his genius and the armies of Byzantium, Belisarius has blunted the first assault of the Malwa hordes. Now he and his allies from all the world yet free face overwhelming numbers in a ring that tightens about them.

There is no room for maneuver and no safety in defeat. The armies of Good and Evil gathered on the fertile plains of Mesopotamia will decide the fate of the world
And the fate of all the future!