The first century which passed after the settlement of the Northmen along the Seine saw "the steady growth of the duchy in extent and power. Much of this was due to the ability of its rulers, to the vigour and wisdom with which Hrolf forced order and justice on the new community, as well as to the political tact with which both Hrolf and William Longsword [son and successor of Duke Rollo or Hrolf, A. D. 927-943] clung to the Karolings in their strife with the dukes of Paris. But still more was owing to the steadiness with which both these rulers remained faithful to the Christianity which had been imposed on the northmen as a condition of their settlement, and to the firm resolve with which they trampled down the temper and traditions which their people had brought from their Scandinavian homeland, and welcomed the language and civilization which came in the wake of their neighbours' religion. The difficulties that met the dukes were indeed enormous. … They were girt in by hostile states, they were threatened at sea by England, under Æthelstan a network of alliances menaced them with ruin. Once a French army occupied Rouen, and a French king held the pirates' land at his will; once the German lances were seen from the walls of their capital. Nor were their difficulties within less than those without. The subject population which had been trodden under foot by the northern settlers were seething with discontent. The policy of Christianization and civilization broke the Normans themselves into two parties. … The very conquests of Hrolf and his successor, the Bessin, the Cotentin, had to be settled and held by the new comers, who made them strongholds of heathendom. … But amidst difficulties from within and from without the dukes held firm to their course, and their stubborn will had its reward. … By the end of William Longsword's days all Normandy, save the newly settled districts of the west, was Christian, and spoke French. … The work of the statesman at last completed the work of the sword. As the connexion of the dukes with the Karoling kings had given them the land, and helped them for fifty years to hold it against the House of Paris, so in the downfall of the Karolings the sudden and adroit change of front which bound the Norman rulers to the House of Paris in its successful struggle for the Crown secured the land for ever to the northmen. The close connexion which France was forced to maintain with the state whose support held the new royal line on its throne told both on kingdom and duchy. The French dread of the 'pirates' died gradually away, while French influence spread yet more rapidly over a people which clung so closely to the French crown." _J. R. Green, The Conquest of England, chapter 8._ NORMANDY: A. D. 1035-1063. Duke William establishes his authority.