The battle that was thus opened was the beginning of a new epoch in Irish history. St. Augustine, first archbishop of Canterbury (597), was ordered (603) to demand obedience to himself from the Celtic churches and the setting aside of their customs. The Welsh and the Irish refused to submit. Augustine had come to them from among the English, who were still pagan, and still fighting for the extermination of the Celts, and on his lips were threats of slaughter by their armies to the disobedient. The demand was renewed sixty years later, in a synod at Whitby in 664. By that time Christianity had been carried over England by the Irish mission; on the other hand, the English were filled with imperial dreams of conquest and supremacy. English kings settled on the Roman province began to imitate the glories of Rome, to have the Roman banner of purple and gold carried before them, to hear the name of "Emperor of the whole of Britain," and to project the final subjugation to that "empire" of the Celt and Pictish peoples. The Roman organisation fell in with their habits of government and their ambitions. In the synod the tone of imperial contempt made itself heard against those marked out for conquest--Celts "rude and barbarous"--"Picts and Britons, accomplices in obstinacy in those two remote islands of the world." "Your father Columba," "of rustic simplicity" said the English leader, had "that Columba of yours," like Peter, the keeping of the keys of heaven? With these first bitter words, with the condemnation of the Irish customs, and the sailing away of the Irish monks from Lindisfarne, discord began to enter in. Slowly and with sorrow the Irish in the course of sixty years abandoned their traditional customs and adopted the Roman Easter. But the work of Columcille was undone, and the spiritual bond by which the peoples had been united was for ever loosened. English armies marched ravaging over the north, one of them into Ireland (684), "wasting that harmless nation which had always been most friendly to the English, not sparing even churches or monasteries." The gracious peace which had bound the races for a hundred and twenty years was broken, and constant wars again divided Picts, Scots, Britons, and Angles.