From Ghazi to Sipahi
The ghazi warriors who provided the original cutting edge of Ottoman expansion were land-hungry freebooters of diverse origins. An increase in the size of this group was essential if the Ottoman state was to continue expanding. The timar system provided an economic basis for a numerous class of such sipahis, whose obedience was ensured by institutionalizing denial of the hereditary principle in the Ottoman law of feudal land-holding, and whose appetite for warfare was stimulated by the enticing prospect of fresh plunder perpetually available across the frontiers of the empire. According to the Venetian ambassador...there were 80,000 sipahis in European Turkey in 1573 [C.E.] and 50,000 in the Asiatic provinces, together with 15,000 sipahis 'of the Porte', household cavalry who were paid by the treasury and did not receive timars. The sipahis remained an unruly class, militarily valuable but politically untrustworthy, whose turbulence it was necessary to balance and control by increasing the numbers and improving the efficiency of public administrators and by establishing a body of household infantry whose effectiveness on campaign and loyalty to the sultan were beyond question. It was in response to these requirements that the Ottomans of the fifteenth and sixteenth centuries developed slavery as a fundamental social institution; organizing by this means a supply of obedient and talented soldiers and administrators on a scale suited to the demands of a great imperialist power.