D'Artagnan had a career in espionage for Cardinal Mazarin, in the years after the first Fronde. Due to d'Artagnan's faithful service during this period, Louis XIV entrusted him with many secret and delicate situations that required complete discretion. He followed Mazarin during his exile in 1651 in the face of the hostility of the aristocracy. In 1652 d'Artagnan was promoted to lieutenant in the Gardes Françaises, and fought at the Battle of Stenay in 1654, as well as in sieges at Landrecies and Saint-Ghislaine, then to captain in 1655. In 1658, he became a second lieutenant in the newly reformed Musketeers. This was a promotion, as the Musketeers were far more prestigious than the Gardes-Françaises.