Popes, like patriarchs, were required to keep an "agent" at the eastern court. The Emperors continued to insist on the right to confirm all papal elections, and, of course, this practically put the election into their hands, as is shown by the elevation of so many "agents" to the papal throne, viz., Vigillus, Pelagius I., Gregory the Great, Sabinian, etc. The Popes, on their installation, were expected to pay tribute to the eastern Emperor.[299:4] Even in questions of doctrine, the Emperor might enforce his will by exiling an obstinate Pope, as in the case of Martin I. (655). During the period from 552 to 800, the papal power was growing stronger all the time, and only awaited a favourable opportunity to issue a declaration of independence. The Italians hated both the Greeks and Lombards as foreign masters. Between the two stood the Pope as the only representative of Italian nationality and the sole champion of Italian independence. The Papacy was in theory democratic, and celibacy made a dynasty impossible. The occasion for a declaration of independence was the Iconoclastic Controversy; the leaders were Gregory II. and Gregory III., who formally excommunicated Emperor Leo and his hierarchy; and the new ally to make the independence good was the family of Pepin in Gaul and Germany. After 772, the papal documents do not bear the name of the eastern Emperor.[300:1] The seventh and eighth centuries in European history reveal the elements of religious and political life in a state of incessant and violent fermentation. Sudden changes took place in the relative position of nations. The old Empire was disintegrating and new kingdoms were appearing. During this period of political transformation, the Church was the only system that persisted in the old channel that it had created for itself. The Papacy, though not yet an acknowledged kingdom in the world, still stood among the political powers as a self-existent organisation, exercising an influence over princes and subjects. The governments were isolated, divided, anarchical. In the Church alone was there unity, order, method, organisation, and supreme purpose. There alone was found facility of communication and cordial interchange of views. The Popes of Rome kept up a constant intercourse with all nations from Asia to the Atlantic and constituted the one recognised unifying force in Europe standing for the highest ideals of the age along all lines.