The Agha was chosen by the Ottoman Sultan, but was not necessarily himself a Janissary.[1] To secure the often uncertain loyalty of the corps, Bayezid II (r. 1481–1512) stopped the practice of appointing the sekban-bashi (the commander of the sekban regiments) to the post, and instead nominated a member of his own household to the post.[2] At the same time, Bayezid founded the Ağa Bölükleri ("Agha's Troops") regiments, initially as the Agha's personal retinue and a means of controlling the corps; eventually these became regular Janissary units, and by the end of the 16th century there were 61 Ağa Bölükleri regiments.[2] During the Devshirme system, the Agha was responsible for checking the new recruited boys on arrival at Istanbul for falsifications or missing persons; his subordinates then examined the boys and allocated them either to the palace service or to the Janissary corps.[3] As the Janissaries' political role increased in the early 17th century, from 1641 on the Aghas were once again appointed from among the Janissary corps.[4]