war belonged to God, to Muhammad and his family, to orphans, to those in need and to travelers. This eventually included slaves, and war captives were given to soldiers and officers to help motivate their participation in wars. Christians and Jews, known as People of the Book in Islam, were considered dhimmis in territories under Muslim rule, a status of second-class citizens that were afforded limited freedoms, legal protections, personal safety, and were allowed to "practice their religion, subject to certain conditions, and to enjoy a measure of communal autonomy" in return for paying the jizya and kharaj taxes. If a dhimmi broke his agreement and left Muslim territory for enemy land, he was liable to be enslaved – unless the dhimmi had left Muslim territory because he suffered injustice there. Dhimmis were protected persons who could not be enslaved unless they violated the terms of protection. Such violations normally included rebellion or treason; according to some authorities this could also include failure to pay due taxes. Failure to pay tax could also result in imprisonment. The Devshirme was a blood tax largely imposed in the Balkans and Anatolia in which the Ottoman Empire sent military to collect Christian boys between the ages of 8 to 18, who were taken from their families and raised to serve the empire. The tax was imposed by Murad I in the mid 1300s and lasted until the reign of Ahmet III in the early 1700s. From the mid to late 14th, through early 18th centuries, the devşirme–janissary system enslaved an estimated 500,000 to one million non-Muslim adolescent males. These boys would attain a great education and high social standing after their training and forced conversion to Islam. Basilike Papoulia wrote that "the devsirme was the 'forcible removal', in the form of a tribute, of children of the Christian subjects from their ethnic, religious and cultural environment and their transportation into the Turkish-Islamic environment with the aim of employing them in the service of the Palace, the army, and the state, whereby they were on the one hand to serve the Sultan as slaves and freedmen and on the other to form the ruling class of the State." Indentured servitude In the 17th to 18th centuries, many white people in Britain, Ireland and European colonies in North America were indentured servants. Sterling Professor of History at Yale University David Brion Davis wrote that: From