Anglo - Turkish piracy Anglo - Turkish piracy or the Anglo - Barbary piracy refers to the collaboration between Barbary pirates and English pirates against Catholic shipping during the 17th century . Anglo - Turkish collaboration . The Protestants and the Muslim " Turks and Berbers " , more precisely the Barbary pirates , collaborated during that period against their common enemy , Catholic Europe . This collaboration has to be seen in the context of the wars of religions and the ongoing mortal battle between Protestantism and Catholicism . At that time , Spain , Portugal , and France , which were implementing anti - Protestant policies , were the target of this Anglo - Muslim collaboration . It also seems that English pirates , who had been active against Spain until 1604 when peace was signed with England , were still inclined to continue the fight and the depredations , although under the protection of a different state , to the embarrassment of the English Crown . Piracy in the ranks of the Muslim pirates of Barbary was also a way to find employment , after King James I formally proclaimed an end to privateering in June 1603 . Further , abandoning England as well as their faith was often a way to financial success , as fortunes could be made by attacking Christian shipping . By 1610 , the wealth of English renegade pirates had become so famous as to become the object of plays , and the king offered Royal Pardon to those who wished to return . Not only the English corsairs participated to this collaboration , but also the Dutch , who shared the same objectives . Catholic ships were attacked and prisoners taken to Algiers or other places of the Barbary Coast to be sold as slaves . The number of these English pirates was significant . Jack Ward , Henry Mainwaring , Robert Walsingham and Peter Easton were among such English pirates in the service of the dey s of the Barbary coast . Some of the most famous Dutch pirates were Zymen Danseker , Salomo de Veenboer and Jan Janszoon . Some of them , such as Ward and Danseker , were " renegade s " who had adopted Islam . Mainwaring attacked the Spanish preferentially , and claimed that he avoided English shipping , but generally ships of all nationalities seem to have been attacked . Walsingham is known to have freed Turkish captives from Christian galley s , and to have sold Christian captives on the North African slave market . Janszoon led long - ranging raids such as the Turkish Abductions in Iceland to sell his slaves on the Barbary Coast . A contemporary letter states : Beyond the shared religious antagonism towards Catholicism , the Barbary States probably offered economic advantages as well as social mobility to Protestant pirates , as the Barbary States were a very cosmopolitan environment at that time . Catholic reactions . France , which had a tradition of alliance with the Ottoman Empire , placed a formal protest with the Ottoman Sultan in 1607 , complaining that English and Dutch pirates were allowed to use North African harbors as bases to raid French shipping . For France , it was a clear conspiracy against Catholicism , described at the time as " Turco - Calvinism " . In order to curb these actions , Spain made a proclamation against piracy and privateering in 1615 . England probably became ambivalent about this sort of piratical collaboration as it attacked Algiers in 1621 in order to free Christian captives there . In 1629 , Louis XIII attacked Salé to free 420 French captives . Louis XIV also later bombarded Algiers in retaliation . Catholic religious orders , especially the Trinitarians and the Lazarists under Saint Vincent de Paul , himself a former slave , accumulated donations to ransom and liberate Christian slaves . It is estimated that the missionaries liberated 1 , 200 slaves until the death of Saint Vincent de Paul in 1660 , for a total of 1 , 200 , 000 livres .