In the days of the Byzantine Empire the attempt to enforce Greek uniformity on all nations resulted in various national stocks (Syrian, Armenian, and Egyptian, for instance) adopting any "heresy" that chanced to be on the tapis, as a protest against what they regarded as "Greek dictation." While the dispute, both doctrinal and national, was still being fought out, the great Mussulman invasions began; and the nationalities in question cheerfully accepted the Mohammedan rule, which gave to them a religious freedom which the Greek Christian Empire had denied. The Arab, and the Turk who followed him, were perfectly willing to see their Christian subjects divided as much as they liked; and recognized the Armenian, Syrian, Chaldaean, and Coptic nations as "_millets_" in their empire; a "_millet_" being the technical term for a subject nation of Christians, organized (as they always were) in a church, under their own hierarchy of Patriarch, bishops, and clergy. Thus these various national churches, all called heretical by both Greeks and Latins, continued to exist under Turkish rule. [Illustration: THE "PICTURE ROCKS" OF BAVIAN. No. 4] In the later days of the Turkish Empire Roman Catholic missions brought education to these Christians; and the Roman Church allowed such portions of these old national churches as could be brought to submit to papal supremacy, to retain their own hierarchy, and their ancient services, expurgated to some extent. All these "Uniat" or "reconciled" bodies are, of course, subject to the Pope, but their members do not, normally, communicate with one another. Historically, one rejoices at the preservation of so many ancient rites and bodies, and the method was sound policy also from the point of view of the proselytizing agents of the Roman Church; for both Nestorian and Jacobite might both be brought to acknowledge the supremacy of a distant Pope, if that Pope's agents had somewhat to give in the way of protection or education, but neither could ever be brought to associate with "that other" whose tenets his church existed to repudiate. Thus, with sound prudence, rules about diocesan jurisdiction that hold elsewhere are dropped in the Middle East; and Mosul boasts at least three Roman Catholic bishops, namely, a Chaldaean or "Nestorian Uniat"[39] Patriarch, with several bishops under him; a Syrian Catholic or "Jacobite Uniat"[39a] bishop, subordinate to the Patriarch of that church at Beyrout; and an "Apostolic Delegate," or Papal Legate, who exercises a general superintendence over all Roman Catholic bishops in Mesopotamia, but has direct spiritual jurisdiction over only the handful of Frenchmen who reside actually in Mosul, and any other "Christian of the Latin rite" who may chance to come that way.