To England her success was the beginning of a career of military glory, which fatal as it was destined to prove to the higher sentiments and interests of the nation gave it a warlike energy such as it had never known before. Victory followed victory. A few months after Crecy a Scotch army marched over the border and faced on the seventeenth of October an English force at Neville's Cross. But it was soon broken by the arrow-flight of the English archers, and the Scotch king David Bruce was taken prisoner. The withdrawal of the French from the Garonne enabled Henry of Derby to recover Poitou. Edward meanwhile with a decision which marks his military capacity marched from the field of Crecy to form the siege of Calais. No measure could have been more popular with the English merchant class, for Calais was a great pirate-haven and in a single year twenty-two privateers from its port had swept the Channel. But Edward was guided by weightier considerations than this. In spite of his victory at Sluys the superiority of France at sea had been a constant embarrassment. From this difficulty the capture of Calais would do much to deliver him, for Dover and Calais together bridled the Channel. Nor was this all. Not only would the possession of the town give Edward a base of operations against France, but it afforded an easy means of communication with the only sure allies of England, the towns of Flanders. Flanders seemed at this moment to be wavering. Its Count had fallen at Crecy, but his son Lewis le Male, though his sympathies were as French as his father's, was received in November by his subjects with the invariable loyalty which they showed to their rulers; and his own efforts to detach them from England were seconded by the influence of the Duke of Brabant. But with Edward close at hand beneath the walls of Calais the Flemish towns stood true. They prayed the young Count to marry Edward's daughter, imprisoned him on his refusal, and on his escape to the French Court in the spring of 1347 they threw themselves heartily into the English cause. A hundred thousand Flemings advanced to Cassel and ravaged the French frontier.