King and Emperor

Shef, the One King, is a visionary and warrior. His accomplishments have changed the history of the Dark Ages as we know it - he has defeated the English, the Pope's army and the Norse in turn. Now, he must face the reborn power of the Holy Roman Empire. While the Gods of Asgard continue to use him as a plaything Shef must defeat Bruno, the German emperor, who wields the Holy Lance which pierced Christ's side.
The terrible invention of Greek Fire threatens Shef's fearsome Viking navy, and he must turn to the East to seek new wisdom. Finally, his quest may lead him to the Holy Grail itself. As Harry Harrison's highly-acclaimed series reaches its climax, not even the gods can predict victor and vanquished.