Devshirme was the Ottoman practice of forcibly recruiting soldiers and bureaucrats from among the children of their Balkan Christian subjects and forcibly converting them to Islam. Wikipedia

The practice of forced recruitment of Christian boys under the Ottoman Empire Wikipedia Disambiguation

Ottoman Empire recruitment practice Wikidata

Systematic collection of non-Muslim children from rural Christian populations of the Balkans, practiced by Ottomans , in which every three or four years 1 healthy boy or young men out of 40 families had to be taken to Istanbul, converted to Islam and educated for military profession or religious disciplines. Wiktionary

Collection of non-Muslim children to be converted to Islam. Wiktionary (translation)