The numerous monasteries founded during the Ottoman period were privately established by individuals on their own lands. These establishments are proof of a social evolution on the islands. Certainly, in general, the great Catholic families converted little by little, but this is insufficient to explain the number of new monasteries. It must be concluded that a new Greek Orthodox elite emerged which took advantage of the weakening of society during the Ottoman conquest to acquire landed property. Their wealth was later cemented through the profits from commercial and naval enterprises. At the beginning of the 17th century, the Orthodox reconversion was practically complete. It is in this context that the Catholic counter-offensive is situated. Catholic missionaries, for instance, envisioned the start of a crusade. Père Saulger, Superior of the Jesuits on Naxos, was a personal friend of Louis XIV’s confessor, Père La Chaise. In vain, he used this influence to push the French king to launch a crusade. The Cyclades had six Catholic bishoprics: on Santorini, Syros, Naxos, Tinos, Andros and Milos. They were part of the policy of a Catholic presence, for the number of parishioners did not justify so many bishops. In the middle of the 17th century, the diocese of Andros contained fifty Catholics; that of Milos, thirteen. Indeed, the Catholic Church showed itself to be very active in the islands during the 17th century, taking advantage of the fact that it was under the protection of the French and Venetian ambassadors at Constantinople, and of the wars between Venice and the Ottoman Empire, which weakened the Turks’ position in the archipelago. The Congregation for the Propagation of the Faith, the Catholic bishops and the Jesuit and Capuchin missionaries all tried to win over the Greek Orthodox inhabitants to the Catholic faith and at the same time to impose the Tridentine Mass on the existing Catholic community, to whom it had never been introduced. The Capuchins were members of the Mission de Paris and thus under the protection of Louis XIV, who saw in this a way of reaffirming the prestige of the Most Christian King, but also to set up commercial and diplomatic footholds. Capuchin establishments were founded on Syros in 1627, on Andros in 1638 (whence they were driven out by the Venetians in 1645 and where they returned in 1700), on Naxos in 1652, on Milos in 1661 and on Paros, first in the north at Naoussa in 1675, then at Paroikia in 1680.