The Jackal Of Nar

His enemies call Prince Richius "the Jackal," but he is merely a reluctant warrior for the Emperor in the fight for the strife-ridden borderland of Lucel-Lor. And though the empire's war machines are deadly, when the leader of a fanatical sect sweeps the battlefield with potent magic, Richius's forces are routed. He returns home defeated--but the Emperor will not accept the loss. Soon Richius is given one last chance to pit the empire's science against the enemy's devastating magic, and this time he fights for more than a ruler's mad whim. This time Richius has his own obsessive quest--and where he hesitated to go for an emperor's greed, for love he will plunge headlong into the grasp of the deadliest enemy he has ever encountered....

This is #1 in Tyrants And Kings Series.