Until the accession of Murad III. (1574) the total effective of the janissaries, including the ajami or apprentices, did not exceed 20,000. In 1582 irregularities in the mode of admission to the ranks began. Soon parents themselves begged to have their children enrolled, so great were the privileges attaching to the corps; later the privilege of enlistment was restricted to the children or relatives of former janissaries; eventually the regulations were much relaxed, and any person was admitted, only negroes being excluded. In 1591 the ojak numbered 48,688 men. Under Ibrahim (1640-1648) it was reduced by Kara Mustafa to 17,000; but it soon rose again, and at the accession of Mahommed IV. (1648), the accession-bakshish was distributed to 50,000 janissaries. During the war of 1683-1698 the rules for admission were suspended, 30,000 recruits being received at one time, and the effective of the corps rising to 70,000; about 1805 it numbered more than 112,000; it went on increasing until the destruction of the janissaries, when it reached 135,000. It would perhaps be more correct to say that these are the numbers figuring on the pay-sheets, and that they doubtless largely exceed the total of the men actually serving in the ranks. Promotion to the rank of warrant officer was obtained by long or distinguished service; it was by seniority up to the rank of _odabashi_, but odabashis were promoted to the rank of _chorbaji_ (commander of an orta) solely by selection. Janissaries advanced in their own orta, which they left only to assume the command of another. Ortas remained permanently stationed in the fortress towns in which they were in garrison, being displaced in time of peace only when some violent animosity broke out between two companies. There were usually 12 in garrison at Belgrade, 14 at Khotin, 16 at Widdin, 20 at Bagdad, &c. The commander was frequently changed. A new chorbaji was usually appointed to the command of an orta stationed at a frontier post; he was then transferred elsewhere, so that in course of time he passed through different provinces.