Around the start of the sixteenth century, Muslim pirates from Algiers began to terrorize the Christian Mediterranean. Like their terrestrial counterparts, they too were indoctrinated in and emboldened by Muhammad's promises: "A campaign by sea is like ten campaigns by land," the prophet had said, "and he who loses his bearings at sea is like one who sheds his blood in the path of Allah." The piratical lust for booty was, predictably, heightened by dreams of "martyrdom."
When Suleiman "the Magnificent"—better known among Muslims as Suleiman "the Ghazi" (jihadi/raider)—became Ottoman sultan in 1520, he instantly took the most notorious of these Barbary pirates, Khair al-Din Barbarossa, into his service and helped him prosecute the sea jihad on Europe. The ensuing reign of terror forced Europeans along the Mediterranean coast to relive the days of their ancestors in the centuries before the Crusades, when the Middle Sea was first inundated with jihad and slave raiding. Over the following two decades, hundreds of thousands of Europeans were enslaved, so that, by 1541, "Algiers teemed with Christian captives, and it became a common saying that a Christian slave was scarce a fair barter for an onion."