But this playing at fighting was not enough for his ambition; and in the war which followed between Charles of Blois and John de Montfort, for the possession of the Duchy of Brittany, he served his apprenticeship as a soldier. As he was not a great baron with a body of vassals at his command, he put himself at the head of a band of adventurers, and fought on the side of Charles and of France. He distinguished himself by a brilliant action at the siege of Vannes in 1342; and after that he disappears from history for some years. In 1351, having shortly before been made a knight, he was sent into England with the lords of Brittany to treat for the ransom of Charles of Blois, who had been defeated and captured by the English in 1347. When Rennes was besieged by the Duke of Lancaster, in 1356, Du Guesclin forced his way with a handful of men into the town, and successfully defended it till June, 1357, when the siege was raised in pursuance of the truce of Bordeaux. For this service he was rewarded with the lordship of Roche d'Airien. At the expiration of the truce he distinguished himself by the defence of Dinan, and here he engaged in single combat with Sir Thomas Canterbury. Shortly afterward he married; and about the same time he passed into the service of France, and greatly distinguished himself at the siege of Melun (1359). In April, 1364, in conjunction with Boucicault, he recovered Mantes and Meulan from the King of Navarre; and in May he defeated the Navarrese under Captal de Buch at Cocherel, and took their leader prisoner. The king now created him Marshal of Normandy and Count of Longueville. At the battle of Auray, in September of the same year, Charles of Blois was defeated and killed, and Du Guesclin taken prisoner, by Sir John Chandos. The grand companies beginning, after the close of the war, to play the part of brigands in France, it was necessary to get rid of them. Du Guesclin was ransomed for 100,000 crowns, and was charged to lead them out of France. He marched with them into Spain, visiting Avignon on the way, and extorting from the Pope a large sum of money and his absolution. Du Guesclin now supported Henry of Trastamare against Peter the Cruel, set the former upon the throne of Castile (1366), and was made Constable of Castile and Count of Trastamare. In the following year he was defeated and captured by the Black Prince, ally of Peter the Cruel, at Najara, but was soon released for a heavy ransom. Once more he fought for Henry, reinstated him on the throne (1369), and was created Duke of Molinas. [Illustration: Bertrand du Guesclin.]