He was born Ponce d'Escouperie in Caunes-Minervois (Aude), Languedoc, a son of Jacques Escoperier and X Armengaud. As a youngster, he wanted to become a priest and was educated in a monastery. He changed his mind, however, and left Languedoc to become a mercenary in the service of Denmark. De la Gardie was promoted to officer and was in charge of a regiment of mercenaries. In 1565, during the Northern Seven Years' War, he was captured by Swedish troops at Varberg and changed allegiance to Sweden. De la Gardie quickly became a favourite of John III of Sweden and in 1569, after only four years in the Swedish service, he received nobility status. In 1571, he was created a baron and was given Ekholmen Castle.