Sallee pirates

Sallee pirates, Barbary pirates, mostly Muslims expelled from Spain, but also European renegades. They operated from the Moroccan port of Salli (now part of Rabat) from the early decades of the 17th century. They harassed Christian trade, and raided the coast of Spain, a particular focus of their hatred, to acquire victims for the slave trade. Salli was nominally under the control of the Emperor of Morocco but in 1627 it broke away and established a self-governing corsair republic. So successful were they that they later extended their activities into the English Channel and the Atlantic, and even as far as Newfoundland, and they could put as many as 60 ships—vessels developed from the Mediterranean tartan and xebec—to sea. These ‘were all very fast sailers and nearly always equipped with oars as well as sails, so fast indeed that the French Admiral Tourville believed that a Sallee rover could only be caught at sea by a former Sallee rover taken as a prize into French service’ ( P. Earle , The Pirate Wars (2003), 44–5).
Uncoordinated expeditions were mounted against them by the British, Dutch, French, and Spanish. These sometimes achieved temporary success, but piracy always broke out again when the expeditions withdrew, and lack of a concerted effort to crush them allowed their depredations to continue well into the 18th century.