Shortly after Henry of Navarre's marriage to Catherine's daughter Marguerite de Valois in 1572, Catherine recruited Charlotte to her elite group of beautiful female spies and informants known as the "Flying Squadron" (L'escadron volant) and she quickly became one of its "most accomplished members".
The Queen Mother's purpose in inviting Charlotte to join the group was for the latter to seduce Navarre, become his confidante as well as mistress, and thus extract information which she would duly pass on to Catherine who would subsequently use it as political leverage. The "Flying Squadron" had a male counterpart in "Les Mignons".
Charlotte quickly became Navarre's mistress and exerted a strong influence over him. His wife
Marguerite recorded in her memoirs:
"Mme de Sauve so completely ensnared my husband that we no longer slept together, not even conversed".
She accused de Sauve ("that Circe") of persuading Henry that she was jealous of de Sauve, with the result that Henry, whose affairs Marguerite had allowed, stopped confiding in her.