Meanwhile the western part of Belgium, the county of Flanders, had developed also in its own way. Assigned by the Treaty of Verdun to the kingdom of France, Flanders did not seek a separation from a country to which it was geographically attached and on whose territory were to be found the seats of its bishoprics and most of its monasteries. The political power of the house of Flanders dates from the time of Count Baldwin I, called Baldwin of the Iron Arm (879), an adventurous ruler, who violently took the daughter of the King of France, his lord, and made her his wife, notwithstanding the vehement protest of her royal father. That marriage brought to the count the rich possessions of his wife and furnished to his heirs an excellent pretext for meddling in the politics of France. The kings of France at the time of the first counts of Flanders were weaklings; moreover, the bishops of Noyon-Tournai, Arras, and Térouanne were not as loyal to their lord as those of Lotharingia were to the Emperor. The political conditions were thus quite different in Flanders, and at a time when the iron policy of Otto I and his heirs subdued the Lotharingian princes, the counts of Flanders succeeded in developing their independence and political influence without much opposition. Baldwin II (910) enlarged his domain by conquering the wealthy regions of Walloon-Flanders[7] and Artois and formed an alliance with England by marrying an Anglo-Saxon princess. Count Arnulf (918) took the title of marquess and tried--though vainly--to overpower the Duke of Normandy, who checked his advance in the south and with it the extension of Flemish conquest beyond the river Canche. Effectively blocked in their efforts to extend their power in the south, the Flemish counts next turned their attention to the north and the east. Successively the islands of Zeeland, the “Four Métiers,” and the county of Alost were subjugated, although already under the feudal authority of the German Empire. The result was that the Count of Flanders became at once a vassal of the King of France and of the German Emperor. By the conquest of the county of Alost, Count Baldwin V was enabled to cross the Scheldt and to advance into Lotharingian territory. The marriage of his son with a princess of Hainaut resulted in uniting both Flanders and Hainaut under the same dynasty. Here again the barrier erected by the Treaty of Verdun was broken down, and for the first time political ties were established on both sides of the Scheldt, between the two parts of Belgium.