This study explores Franco-Papal relations, and their effect on the French Church and State, from Henri IV's conversion to Roman Catholicism in 1593 until his death in 1610. Because Henri IV's primary concern, even in matters involving the Papacy or the Gallican Church, was to protect his kingdom from Habsburg encroachment, he was willing either to abandon his Protestant allies abroad, or to adopt reform measures, such as the decrees of the Council of Trent, that might weaken his own authority or disturb the peace of his kingdom. This caused repeated conflicts with the Counter-Reformation Popes Clement VIII and Paul V, to whom the primary enemy was always the infidel and the heretic. Nevertheless both sides realized that they needed each other to maintain their independence of Spain.