"Moslems alone were obliged to perform military service, and were thus alone eligible for the tenure of land. This was distributed as a reward for service and provided a source of recruitment in the form of military fiefs, free of taxes. Christians were exempt from military service, hence benefitted from no such landed rights. Instead they paid a head tax for the army's support. In the country districts this made them subservient in status to the landholding Moslems. Thus they tended to live and work in the cities and towns, where such civil disabilities were counterbalanced by economic advantage. But through voluntary conversion to Islam, the Christian became automatically an Osmlani, with his origins soon forgotten, enjoying freedom from taxation, the right to hold land, opportunities for advancement, and a share in the benefits of the Moslem ruling elite. Hence, at this stage of Ottoman history in Asia, the growing number of converts to Islam.
Feudal though it was, this Ottoman system of land tenure through military fiefs differed essentially from the feudal system in Europe, in that the landholdings were small and above all seldom hereditary. For all land was the property of the state. Thus at this stage there was to arise in the Ottoman empire no landed nobility, such as prevailed throughout Europe. The sultans retained absolute ownership of the soil they conquered. Moreover, as they continued to conquer, more holdings became available as rewards for more soldiers. Within the framework of this system Orkhan now organized, with the initial advice of his brother, Ala-ed-Din, a regular standing army under the sovereign's command, a professional military force on a permanent war footing, of a kind not to be emulated in Europe for a further two centuries."
Lord Kinross, The Ottoman Centuries, p. 33