Charles fought for Henry at the battle of Coutras in 1587, was then introduced and secretly engaged to Henry's sister Catherine. He attended the Estates General at Blois in 1588, fought back the League's forces at the battle of Saint Symphorien in 1589, was taken prisoner at Château-Giron and, escaping from Nantes, joined forces with Henry at Dieppe. After the battle of Ivry he led the king's cavalry in besieging Paris in 1590, and proved his worth at the sieges of Chartres in 1591 and of Rouen in 1592. Although he briefly joined in the scheme of his brother Charles, Cardinal de Bourbon, to form a third party in the kingdom, he attended Henry's coronation in 1594. He fought loyally at the successful siege of Laon. Peace having been concluded with Spain, he commanded troops in the war in Savoy in 1600.