Charles de Gontaut, duc de Biron (c.–31 July 1602) was a French noble, military commander, Admiral, Marshal and governor during the final days of the French Wars of Religion. The son of Marshal Armand de Gontaut, baron de Biron who had served the crown militarily throughout the religious wars, Biron made his entry into French politics in the late 1580s. Initially a follower of the chief royal favourite Épernon by 1589 he was a candidate to become Admiral of France. In August 1589 Henri III was assassinated, and Biron and his father transferred their loyalties to the Protestant Henri IV putting them at war with the Catholic ligue. He fought at the royalist victories of Arques and Ivry in late 1589 and early 1590, during which he developed a reputation as an exceptional commander. In 1592 he became Admiral of France, a post he would hold for two years, before being compelled to trade it for the title of Marshal so that it could be offered to a rebel. In 1593 Biron invaded Bourgogne, and succeeded in capturing many villages, but was unable to secure any major cities. In 1595 he would again invade Bourgogne with considerably more success, Beaune, Auxonne, Autun and finally Dijon falling to him in late May of that year. During the campaign, Henri would grant him the governate of Bourgogne. A Spanish army under the Constable of Castilla invaded in response and joined forces with the duke of Mayenne lieutenant-general of the ligue. Having called on Henri for support, Biron and his king would best the Constable and duke against the odds at Fontaine-Française.