The role of Ottoman naval infantry originated in Orhan's conquest of the Karasi Beylik and the capture of its fleet. From then on Janissaries and Azaps were sometimes deployed as marines during the 14th Century. The Deniz azaps were used during the 16th Century; while troops called Levend (Bahriyeli) were raised on and off over the centuries - over 50,000 of them by the late 18th century. The last raised units were the "Ta'ifat al Ru'sa" (corsair captains militia) recruited from among the North African Arabs and indigenous Berbers. Ottoman marines were part of the Ottoman navy.