GUESCLIN, BERTRAND DU (ga klan'), Constable of France; born near Dinan in the district of Rennes, about either 1314 or 1320. From his boyhood upward he excelled in all martial exer cises. In the contests between Charles do Blois and Jean de Montfort for the dukedom of Brittany he took part with the former, especially distinguishing himself at Vannes (1342). After King John had been taken prisoner by the Black Prince at the battle of Poitiers in 1356, Du Guesclin contended success fully against the English, his valor and military skill being especially shown at Rennes (1356) and Dinan (1357). Then, entering the service of the Dauphin, afterward Charles V., he took Melun (1359) and several other fortified towns, and freed the Seine from the English. On Charles' accession to the throne in 1364 Du Guesclin was created governor of Pontorson, and in May of the same year gained the battle of Cocherel against Charles the Bad of Navarre. But on Sept. 29 following he was de feated and taken prisoner by the Eng lish, under Sir John Chandos, at the battle of Auray, and only liberated on payment of a ransom of 100,000 livres.
He next supported Henry, Count of Trastamare, against Pedro the Cruel, King of Castile, but was defeated and taken prisoner by the Black Prince near Najera (1367). Being again ransomed on payment of a large sum, Du Guesclin renewed the contest, and in 1369 de feated and captured Pedro at Montiel, and placed the crown of Castile on the head of Henry of Trastamare. Immedi ately afterward he was recalled by Charles V. of France, at that time hard pressed by the English, and was raised to the dignity of Constable of France. In the year 1370 Du Guesclin opened his campaigns against the English, and in a few years the whole of their posses sions were in the hands of the French, with the exception of a few fortified towns. While assisting at the siege of Chfiteauneuf de Randon, in Languedoc, Du Guesclin was taken ill, and died July 13, 1380.