Du Guesclin now began to achieve the high emprise of re-annexing to the crown of France those provinces which the gallantry of the Black Prince had wrested from it. Charles could not give him many troops; but the noble knight sold his estates in order to raise men-at-arms, and his wife parted with the ornaments becoming her station, in order to purchase lances and harness. He was soon surrounded by four thousand soldiers. They were chiefly levied in Normandy, and their rendezvous was Caen. Du Guesclin threw an air of chivalry over his emprise, for he introduced the usage of fraternity of arms. He chose for his own brother, Olivier de Clisson, or Du Guesclin, a knight whose name is mentioned with honour in all the great battles of the time. These two Breton cavaliers signed at Pontoison the act of their fraternity, whereby they engaged to defend the estate, life, and honour of each other.[153] Du Guesclin then fell upon the English at Pontvelain with the force of thunder: most of them were taken prisoners; and Sir Robert Knowles, their leader, fled to Brittany, and concealed his head for shame, during the rest of his life in the castle of Derval.[154] The Black Prince was then at Bourdeaux, enfeebled by sickness: he had wasted his constitution in the peninsular war; for the climate of Spain was not so favourable to the health of Englishmen in those days as it has been found in later times. Instead of being able to gird on his armour and display his chivalry, Edward had scarcely strength to follow the counsel of his leeches to return to England. He left the Duke of Lancaster to preserve the English dominion in France from total ruin. The year 1371 was a blank in the chivalric history of Du Guesclin, but the following spring he continued his attempt to subjugate Poictou. Many cities were sacked; and the abhorrence with which the cruelties of Olivier de Clisson were regarded by his own army may warrant the conjecture that inhumanity was not general. At the close of 1372, Poictou was entirely subdued. In the next year, Du Guesclin continued his conquests, and Guienne became the subject of his victories. The Duke of Lancaster was the successor of the power, but not of the chivalry, of the Black Prince; and De Mountfort, whom Edward sent to France as the opponent of Du Guesclin, not only recovered nothing, but lost much of Brittany; and thus, by the genius and fortune of one chivalric hero, all the bright visions of glory created in the fervid imaginations of our Edwards were blighted, and France recovered her station among the high powers of Europe. [Sidenote: Du Gueslin's death before Randan.] [Sidenote: His character.]