The unity of Charlemagne's Empire existed in name alone. The agglomeration of essentially different races only served the purpose of emphasising the distinctions of blood and climate which were to be the eternal bars against unnatural union. But the residuum of separate nations was some time in making its appearance. Their various rulers would not accept the inevitable without a struggle; and in that struggle the only power that gained was the Church. France had no sooner thrown off the German yoke than she professed obedience to her great ecclesiastics. In Neustria the only life and strength left after the Empire died was in the Church. For the land was but a waste of untilled soil, sparsely inhabited by serfs, and divided among the overlords, and of these latter the richest were the abbots and the bishops, round whose palaces and monasteries clustered the towns for their defence. But their temporal power was soon destined to decay. The empire of the mind they might regain; their leadership of France was lost the instant that the Northmen's ships appeared upon the Seine. When the serfs of Neustria first heard the ivory horns of the Vikings echoing along their river's banks, and saw the blood-red banner of the North against the sky, few men realised that the invaders were to weld them into the strongest Duchy of the West, and finally to make France herself arise as an independent nation out of Europe. They fled, these spiritless and defenceless villagers, to the nearest abbey's walls, they hid before the altars which held the relics of their saints, but neither relics nor sanctuary availed to save, as the monks of St. Martin at Tours, of Saint Germain des Pres at Paris could testify. These barbarians used the Christian rites merely to advance their own base purposes. Ever since Harold had won a province for a baptism each pirate chief in turn was the more eager to insist upon such lucrative religion. When they could not make capital out of "conversions" they took gold and provisions as the price of temporary peace. By degrees they gave up going home in winter. The climate of these southern lands was tempting. In various parts of France along the river-mouths, just as they had taken the highway of the Humber into the heart of Britain, they made their scattered settlements, even as far inland as Chartres. But only one was destined to be permanent, and this was made by Rolf, Rollo, or Rou, in Rouen, the kernel of the Northern province. In 841 Ogier the Dane had sailed up the "Route des Cygnes" to burn the shrines of St. Wandrille and Jumieges, to pillage Rouen, even to terrify Paris. After him came Bjorn Ironside and Ragnar Lodbrog. Twice they reached Paris, knocking at the gates to pass through towards the vineyards of Burgundy. In 861 they made a kind of camp upon an island between Oissel and Pont de l'Arche. At last in 876 came Rolf the Ganger, the King of the Sea, and made Rouen his headquarters.