The reunion of the Empire would be maintained by Louis and his heirs, but only at the cost of tremendous turmoil. Roman Catholicism and Eastern Orthodox Christianity had diverged significantly in ritual and belief, and each, of course, had its own supreme pontiff. The Orthodox were not willing to abandon their patriarchate and swear allegiance to Pope Leo III and his successors, and their resistance to religious reunification led to a series of religious civil wars which lasted well into the tenth century.

The Christian wars might have been worse had it not been for the continuing threat from the "Saracens," as Muslims were then known. In Charlemagne's day, the Moors had controlled much of the Mediterranean, and although they had been driven from their holdings in Spain, they remained a potent adversary. It was fear of Muslim invaders which would finally lead to the Synod of Aachen in 944 at which the Eastern and Western forms of Christianity were officially reconciled. That reconciliation allowed the Orthodox to maintain their distinctive liturgy and recognized the Eastern patriarchate as legitimate, though subject to Rome: the patriarch was granted the title of "Archbishop-Cardinal of the East."

Thus unified, the Christian world turned its attention to its longtime common foe, launching a series of "crusades"--wars for the Cross--beginning in 1001. The result of the first of those wars was the seizure, in 1006, of Jerusalem, where a Christian kingdom would be established under John Prester. Other successes followed, and in 1116, the Caliphate of Baghdad would fall.

Islam would never recover. By the twenty-first century, it would be a remnant faith held largely in isolated regions such as the desolate Arabian Peninsula. But the fall of Islam would have unfortunate consequences for Christendom as well, and for the scattered Jewish people, who under the Caliphate had been recognized as "people of the Book" and, though relegated to inferior status as "dhimmi," protected from outright slaughter.

The Caliphate had ironically become a refuge for classical learning during Europe's religious wars, and its fall was accompanied by a wave of destruction directed against "pagan" books and scholars. Today, Persia, once the center of Islamic culture, is a Christian backwater to which the railroad has not yet come, let alone such innovations as electric lighting and the steam automobile, which have so transformed Europe and Columbia in the past thirty years.

As for the Jews, they were to endure centuries of persecution which would all but exterminate their faith in Europe. Large Jewish communities would remain only in Asia and Africa, to which some Jews managed to flee in the ninth and tenth centuries. Today, of course, growing numbers are to be found in Christendom, where well-meaning folk have pressed for them to be permitted such liberties as property ownership.