Robert Davis estimates that 1 million to 1.25 million white Christian Europeans were enslaved in North Africa, from the beginning of the 16th century to the middle of the 18th century, by slave traders from Tunis, Algiers, and Tripoli. Apparently these numbers do not include those Europeans enslaved by Morocco and other traders along the Mediterranean Sea. In addition, about 700 Americans were held captive in this region as slaves between 1785 and 1815. Many of the captured slaves died during the voyage to North Africa from disease and inadequate water and food. The survivors faced a bleak future as they were sold in slave markets and thereafter put to work.
Davies, Robert. (2004). Christian Slaves, Muslim Masters: White Slavery in the Mediterranean, the Barbary Coast, and Italy, 1500-1800. New York: Palgrave Macmillan.