There were many advantages in getting rid of galley-slaves. A galley could not make a long cruise: it was so packed with people, with sailors, soldiers, and hundreds of oarsmen, that huge quantities of food were needed, and only enough could be stowed away to last for a short time. But sails do not need food, and the hold could then be filled with ample stores to last a crew for a long time. Then, again, the slaves were always a source of danger. They were ready to rise on their masters if they had a chance, and help the other side. So the rovers went to work with a will and built "round ships" or "tall ships," as the sailing vessels were called. In the handling of these new ships they were instructed by English and Flemish pirates, and before long they became dreaded far beyond the limits of their old cruising grounds, when they had nothing but galleys.

Now they passed the Straits and bore boldly out into the Atlantic. They seized vessels on the high seas as coolly as they had seized them in the Mediterranean, and proved as skilful in handling their new craft as they had been in working the galleys. Between 1609 and 1616 the Algerine rovers captured the huge number of four hundred and sixty-six British vessels, and carried their crews into slavery.

In 1617 the Corsairs fell upon Madeira, laid the island waste, burned and slew and pillaged, and sailed home to Algiers with twelve hundred captives. In 1627 a German renegade in command of three pirate ships actually sailed right away north to Iceland, and carried hundreds of captives back to Barbary. In a letter written home about this time by the English consul at Algiers, he draws a sad picture of the fate of the English captives taken within a few years previously. He says that the Corsairs demand ransoms, and: "They say that unless you send speedily, they will go to England and fetch men out of their beds, as they commonly used to do in Spain."

Within a few years these very words came true. In 1631 a daring pirate, Murad Reis, a Flemish renegade, made a descent on the shores of England. He passed thence to Ireland, and on the 31st of June he landed his men by night and made a raid upon the little town of Baltimore, sacked it, and carried off many of its inhabitants. Father Dan saw these poor folk in Algiers, and he says: "He (Murad Reis) carried off 237 persons, men, women, and children, even those in the cradle. That done, he brought them to Algiers, where it was pitiable to see them exposed for sale; for then they separated wives from their husbands, and infants from their fathers. They sold the husband to one and the wife to another, tearing the daughter from her arms, without any hope of ever seeing her again. I heard all this at Algiers from several of these slaves, who assured me that no Christian could witness what took place without melting into tears, to see so many honest girls and so many well-brought-up women abandoned to the brutality of these barbarians."

Murad Reis was followed by other Corsair captains into British waters, and the pirates became a terror in the narrow seas between England and France and between England and Ireland. The ports in the south-west were haunted by them. They lay out to sea off such places as Plymouth, Exeter, Barnstaple, and waited for merchant ships to leave the port, or fishermen to put out with their nets. In 1636 the Corsairs were so numerous and so closely did they watch the shore and snap up every vessel, great or small, which left the shelter of the haven, that ships lay idle at the wharves, and fishermen were idle ashore. Owners would not risk their ships, seamen would not go in them, and fishermen feared to be made captives if they ventured into deep water to shoot their nets. No knowledge of the coast or the shoals or the currents was of any avail to escape the rovers. The latter had plenty of English and Irish captives, fishermen and seamen, whom they forced to pilot their vessels, and thus their ships were handled as well and safely as those which belonged to the coast.

A newsletter of 1646 says: "Those roguish pirates which lie upon the western coast have taken from the shore about Penzance, near St. Michael's Mount, sixty men, women, and children. This was in the night, for in the day these rogues keep out of sight for fear of the king's ships." In the same year a petition was sent to the king begging him to deal with the evil. The petition stated that there were more than three thousand poor English "in miserable captivity, undergoing divers and most insufferable labour, such as rowing in galleys, drawing carts, grinding in mills, with divers such unchristianlike works most lamentable to express, and most burdensome to undergo, withal suffering much hunger and many blows on their bare bodies, by which cruelty many, not being able to undergo it, have been forced to turn Mohammedans."