When the Roman empire was broken in pieces by the northern invaders, the body of the Roman Church and clergy belonged to the subdued and enslaved race. The Franks, Northmen, and Anglo-Saxons were then altogether heathen; but many of the invaders--as the Visigoths and Ostrogoths, the Vandals, Burgundians, Heruli, and Longobards--were Christians; but, being Arians (Unitarians), they were enemies of the Trinitarians, and treated the Roman clergy as they did the rest of the subdued population. The Roman clergy, however, finally succeeded in superseding the Arian dogmas by their own, and they then constituted the sole expounders of Christian doctrine. Moved then by the Christian spirit, as well as by consanguinity with the enslaved population, they never failed to impress on the conquerors, whether heathen or Christian, their duties toward their slaves. They also continued to promote manumissions by declaring them meritorious before God. These manumissions were performed at the sacred altar with all the pomp and impressive rites of the Church, and were often extorted from the slaveholding barbarian in his last agonies. As before, so during the first centuries of the Germanic settlements of Western and Southern Europe, the Church never recognized the right of one man to enslave another; but rather through the voice of Gregory the Great, bishop, pope, or saint, reaffirmed the ancient axiom of the Roman jurist: "_Homines quos ab initio natura creavit liberos--et jus gentium jugo substituit servitutis_." The efforts of Gregory the Great, as also those of his predecessors and successors, were directed toward stopping the infamous slave traffic, first in Christian slaves, and then in Jews, Mussulmans, and all heathen. The Roman Church and its leaders unceasingly condemned the slave-trade, and the popes menaced with excommunication the traffickers in Mussulman prisoners in Rome, Lyons, Venice, etc., as also those Germans who afterward, in the ninth, tenth, and eleventh centuries, enslaved the prisoners of war which they made among the Slavonic tribes, Christian and heathen. The popes have likewise perpetually condemned the African or negro slave-trade, from its beginning down to the present day. Gregory XVI. interdicts "all ecclesiastics from venturing to maintain _that this traffic in blacks_ is permitted under any pretext whatsoever;" and prohibits "teaching in public or in private, in any way whatever, any thing contrary to this apostolic letter." Explicit words of this tenor, coming from the pope, were generally considered as expressing the spirit of the Papal Church. In the Roman, as in all other churches and sects, however, both clergy and laity were wont to interpret all such mandates according to their own convenience.