In 1640, the Principality of Sedan was an independent state, whose prince, Frédéric de la Tour d'Auvergne, welcomed French Protestants and other factions hostile to France and Cardinal Richelieu. He also took part in the "Princes de la paix" conspiracy with the comte de Soissons and Henri II de Guise, aiming to re-establish the privileges of the great feudal lords. Louis XIII sent an army to put an end to his schemes, and so Frédéric asked for help from his personal friend Ferdinand III, the Holy Roman Emperor, who duly sent it.