The Reformation had some slight effect at Ragusa about this time, and during the archbishopric of Crisostomo Calvino (the name is a curious coincidence) some preachers were permitted to censure the loose morals of the clergy and even advocate changes in the statutes of the Church. But the movement was short-lived, and the Senate had the books of the Ragusan Matteo Flacco (born in 1520), who was suspected of heresy, burnt by the public executioner. After the death of Crisostomo in 1575 the Jesuits, who had made their first appearance in 1559 as missionaries, established themselves permanently and set up a college and a church. Thus all traces of Protestantism were stamped out. A new disturbance was now caused by the Uskoks, a gang of Christian pirates. Originally these men were refugees from the lands occupied by the Turks. Many, as we have seen, settled at Ragusa and in other Dalmatian towns; but wherever they were they revenged themselves on the usurpers by raiding their territory, plundering their caravans, and keeping up a constant guerilla warfare on the frontiers. Clissa became their chief stronghold, whence they conducted operations against the Infidel; but when, in 1537, the Turks besieged and captured it, the Uskoks were forced to fly once more. The Emperor Ferdinand gave them a refuge at Segna (Zengg) in the Quarnero, a town protected on the land side by impassable mountains and forests. From Segna they continued their raids into Turkish territory, and also began operations by sea. The place soon became a refuge for outlaws of all nations, and the Uskoks ended by becoming as notorious pirates as the Narentans had been of old. They were always a trouble to the Ragusans, sometimes because they captured their galleys, and sometimes because by attacking the Turks they involved the Republic in difficulties with the Porte, who accused it of protecting the freebooters because they were Christians. In 1577 numbers of them were still hanging about in the Dalmatian mountains, and made raids as far as Trebinje, while others from Segna harried Turkish merchantmen. They professed to regard the Ragusans as vassals of the Sultan, and plundered their ships too; but the latter were able to give as hard knocks as they received, and in one encounter killed one of the Uskok leaders. Peace was restored through the mediation of Austria under whose protection the Uskoks were. But the Turks persisted in regarding the Ragusans as the accomplices of the pirates, and again the Sandjakbeg threatened to lay waste their territory. On the land side the Republic was vulnerable, while on the sea her shipping had suffered heavily in the Spanish wars. The incident ended in the Ragusans bribing the enemy into a more reasonable attitude.