Lady-in-waiting and confidant to France’s queen, Anne of Austria, Marie de Rohan, duchess of Chevreuse (1600–1679), traveled between two enemy kingdoms: Spain and France. After a failed conspiracy against Louis XIII, the duchess abandoned France and moved to Spain in 1637 and years later to Brussels, the court of the Spanish Netherlands. She organized political opponents against Cardinal Richelieu and f inally moved to London in 1638, where the leader of Richelieu’s opponents, Marie de Medici, Henrietta María’s mother, later came to live. On one occasion, for example, after meeting with Philip IV, Isabel of Borbón, and the count-duke of Olivares, she was sent to London to propose an alliance between Spain and England against France. This chapter investigates the purpose of the duchess’s constant travels across several European kingdoms on her secret diplomatic missions.