The Ottoman Empire was vastly successful from 1281 until roughly 1922, and its military was one of the main factors for its long maintained rule over much of the Mediterranean world. The military of the Ottomans was highly organized and very specific. The army was made up of elite fighting corps called janissaries. Janissaries were soldiers who were from non-Muslim families originally. They would be taken as small children and converted to Islam. They would then be raised with only one purpose, to be the private guards and army of the Sultan.
The children were taken from throughout the empire, but most of them were from Christian families, and they were often from the Balkans. The fact that the children were being incorporated into the powerful empire helped to ease over the transition when the Ottomans would take over a given area, at least in some parts. In some areas there was great resentment because children were taken from families with names, they did not recruit orphans. The position of janissary was also hereditary, if a child grew up a janissary, he would be able to marry and his children would be janissaries.
The janissaries that proved to be the smartest and had the most promise had access to high levels of education and were close advisors to the Sultan. These soldiers were called viziers. Others who showed political promise were sent to govern provinces in the farther off areas of the empire. The men who were sent to govern were called pashas or beys. The pashas or beys were in charge of collecting the taxes for the Sultan and maintaining peace in those areas.
The janissaries who were trained to fight then served as a “crack fighting force” for the Sultan. The fighters were very famous for their training as horsemen, foot soldiers, skilled warriors with various weapons, and cannon power (which was especially remarkable because few of their enemies had access to such weaponry in that time). Basically, the soldiers’ home was their regiment because they had been permanently removed from their families and homeland. The military was all they ever knew, they were essentially brainwashed into service. The regiments, however, were organized into a hierarchy that sometimes was flexible enough for democratic decision-making. Another unique thing about the regiments was that there was free communication between the ranks. Even the lowest member of a regiment could speak freely and openly to a janissary who had been there 20 years.
The warriors were taught and believed that they were “chosen to serve the Sultan in the name of Islam and Allah”. They were legally slaves, but at the same time they were very privileged members of society. They had huge amounts of land and estates, tax cuts, excellent marriage and social ties, and very close contact with the Sultan’s royal household. Each large city in the empire would have a janissary neighborhood with huge homes and rich surroundings. They gave over their entire lives to the Sultan for this privilege. By roughly the 17th and 18th centuries, the janissaries were not very much a crack military group as much as a network of powerful trained officials and protectors throughout the controlled territories.
CatherineB says the system of recruiting Christian boys was known as the 'devsirme'
Taken from information from a lecture by Dr. Nancy Stockdale