Arnulf I, having secured Douai and Arras, turned his attention towards Normandy, but his progress was soon checked in that direction. His seal, which has been preserved, is the oldest feudal seal known, and the story of his life, the _Sancta prosapia domini Arnulfi comitis gloriosissimi_, was the origin of the collection of annals and chronicles in Latin, French and Flemish which formed, in the sixteenth century, the well-known _Excellente Cronijke van Vlaenderen_. His son and grandson gave up all attacks against Normandy and endeavoured to extend their possessions towards the east and south. Baldwin IV seized Valenciennes, in Hainault, and held it, for some time, against a coalition including the emperor, the King of France and the Duke of Normandy. He was finally obliged to restore the town in 1007, but, a few years later, succeeded in obtaining a portion of Zeeland and Zeeland Flanders ("Four Metiers"). In spite of the efforts made by the emperors to fortify the line of the Scheldt at Antwerp and Valenciennes, his successor, Baldwin V, the Bearded, crossed the river, and, after pushing as far as the Dendre, obtained from Henry II the investiture of the country of Alost and Zeeland. This was called "Imperial Flanders," as opposed to French Flanders, and the count, though nominally subjected to the rule of king and emperor, acquired from his intermediate position a new prestige. Like the dukes of Burgundy, four centuries later, he only lacked the title of a sovereign. "The kings," according to William of Poitiers, "feared and respected him; dukes, marquises, bishops trembled before him." When Henry I of France died, Baldwin was unanimously chosen to act as regent until young Philip came of age. The latter called him "his patron, the protector of his childhood"; he called himself "_regni procurator et bajulus_." The regency ended in 1065, at a time when William of Normandy, who had married one of Baldwin's daughters, was preparing to invade England. The mere threat of a diversion on the Somme would have prevented this expedition, whose consequences were to prove later on so dangerous to France. But Baldwin acted as a Belgian, not as a French prince. It suited his policy to create a rival to his suzerain. Far from hampering William, he allowed a number of his subjects to take an active part in the enterprise. [_BRUGES AS CAPITAL_] The marriage of Baldwin's eldest son with Richilda of Hainault and of his second son Robert with Gertrude of Holland suggested the possibility of an early unification of Belgium under the counts of Flanders. According to Gilbert of Bruges, the two sons of Baldwin were "like powerful wings sustaining him in his flight."