The writings of Pithou, Richer, and Dupuy, and above all the rising influence of the Jansenist party helped to spread the Gallican teaching among the French clergy, and to make them more willing to yield obedience to the king than to the Pope. The Abbot of St. Cyran attacked the authority of the Holy See, but fortunately the extreme nature of his views, and the need felt by both the priests and the bishops of France for the intervention of the Holy See against the Jansenists, served to restrain the anti-papal feeling, and to keep the leading theological writers, like Duval, Du Perron, Ysambert and Abelly, free from any Gallican bias. The accession of Louis XIV. (1661) marked a new era in the history of the Gallican Liberties. He was young, headstrong, anxious to extend the territories of France, and determined to assert his own supreme authority at all costs. With Louis XIV. firmly seated on the French throne, and with the Jansenist party intriguing in the Parliament of Paris, which had shown itself hostile to papal claims, it was not difficult to predict that the relations with the Holy See were likely to become unfriendly. The Duke of Crequi,[1] Louis XIV.'s ambassador at Rome, set himself deliberately to bring about a complete rupture. Owing to an attack made by some Corsicans of the papal guard on the French embassy, the ambassador refused to accept any apology and left Rome, while Louis XIV. dismissed the nuncio at Paris, occupied the papal territories of Avignon and Venaissin, and despatched an army against the Papal States. Alexander VII. was obliged to yield to force, and to accept the very humiliating terms imposed upon him by the Peace of Pisa (1664).