To staff their military and their government, the Ottoman sultans used a selection system called \_________, begun in the late 14th century and expanded in the the 15th and 16th centuries. Through this system, Christian boys who were subjects of the empire were recruited by force to serve in the Ottoman government. Boys ages 8 to 20 were taken each year from conquered Christian lands in Europe. After converting to Islam, they were taught various skills in politics, the arts, and the military.