At first, the soldiers serving in these corps were selected from the slaves captured during war. However, a new system commonly known as devshirme was soon adopted. In this system children of the rural Christian populations of the Balkans were conscripted before adolescence and were brought up as Muslims. Upon reaching adolescence, these children were enrolled in one of the four imperial institutions: the palace, the scribes, the Muslim clergy, and the military. Those enrolled in the military would become either part of the Janissary corps, or part of another corps. The most promising were sent to the palace school (), where they were destined for a career within the palace itself and could attain the highest office of state, Grand Vizier, the Sultan's powerful chief minister and military deputy.