[9] By the seventeenth century, due to a dramatic increase in the size of the Ottoman standing army, the corps' initially strict recruitment policy was relaxed.

Steadily the Ottoman military power became outdated, but when the janissaries felt their privileges were being threatened, or outsiders wanted to modernize them, or they might be superseded by their cavalry rivals, they would rise in rebellion.

Ottoman documents from the levy of the winter of 1603-1604 from Bosnia and Albania wrote to draw attention to some children as possibly being Jewish (şekine-i arz-ı yahudi).

[16] It was a similar system to the Iranian Safavid, Afsharid, and Qajar era ghilmans, who were drawn from converted Circassians, Georgians, and Armenians, and in the same way as with the Ottoman's Janissaries who had to replace the unreliable ghazis.

While they advanced their own power, the Janissaries also helped to keep the system from changing in other progressive ways, and according to some scholars the corps shared responsibility for the political stagnation of Istanbul.

[16] Greek historian Dimitri Kitsikis in his book Türk Yunan İmparatorluğu ("Turco-Greek Empire")[25][page needed] states that many Bosnian Christian families were willing to comply with the devşirme because it offered a possibility of social advancement.

Another was Sokollu Mehmed Paşa, a Bosnian Serb who became a grand vizier, served three sultans, and was the de facto ruler of the Ottoman Empire for more than 14 years.

Trade and commercial activity replaced the disciplined military service of earlier centuries, and the Janissaries were willing to engage in violent acts of rebellion to protect their private interests in an increasingly decentralized and chaotic Ottoman Empire.

They wore unique uniforms, were paid regular salaries (including bonuses) for their service,[27] marched to music (the mehter), lived in barracks and were the first corps to make extensive use of firearms.

They campaigned with their own medical teams of Muslim and Jewish surgeons and their sick and wounded were evacuated to dedicated mobile hospitals set up behind the lines.

The social status of devşirme recruits took on an immediate positive change, acquiring a greater guarantee of governmental rights and financial opportunities.

[33][34] As borders of the Ottoman Empire expanded, the devşirme was extended to include Armenians, Bulgarians, Croats, Hungarians, Serbs and later Bosniaks,[35][36][37][38][39] and, in rare instances, Romanians, Georgians, Circassians, Ukrainians and southern Russians.

This reflected not only the Ottomans' greater need for manpower but also the shorter training time necessary to produce skilled musketeers in comparison with archers.

Membership was opened up to free-born Muslims, both recruits hand-picked by the commander of the Janissaries, as well as the sons of current members of the Ottoman standing army.

This symbolized the "kaşık kardeşliği", or the "brotherhood of the spoon", which reflected a sense of comradeship among the Janissaries who ate, slept, fought and died together.

Janissaries trained under strict discipline with hard labour and in practically monastic conditions in acemi oğlan ("rookie" or "cadet") schools, where they were expected to remain celibate.

[16] Even after the rapid expansion of the size of the corps at the end of the sixteenth century, the Janissaries continued to undergo strict training and discipline.

The Janissaries experimented with new forms of battlefield tactics, and in 1605 became one of the first armies in Europe to implement rotating lines of volley fire in battle.

In the classical period, Janissaries were only one-tenth of the overall Ottoman army, while the traditional Turkish cavalry made up the rest of the main battle force.

[1] Beginning in the 1530s, the size of the Janissary corps began to dramatically expand, a result of the rapid conquests the Ottomans were carrying out during those years.

[51] The Ottoman Empire used Janissaries in all its major campaigns, including the 1453 capture of Constantinople, the defeat of the Mamluk Sultanate of Cairo and wars against Hungary and Austria.

In battle the Janissaries' main mission was to protect the Sultan, using cannon and smaller firearms, and holding the centre of the army against enemy attack during the strategic fake forfeit of Turkish cavalry.

They would also limit the enlistment of new Janissaries to their own sons who did not have to go through the original training period in the acemi oğlan, as well as avoiding the physical selection, thereby reducing their military value.

When Janissaries could practically extort money from the Sultan and business and family life replaced martial fervour, their effectiveness as combat troops decreased.

The stage was set for a decadent evolution, like that of the Streltsy of Tsar Peter's Russia or that of the Praetorian Guard which proved the greatest threat to Roman emperors, rather than effective protection.

In September 1730, janissaries headed by Patrona Halil backed in Istanbul a rebellion by 12,000 Albanian troops which caused the abdication of Sultan Ahmed III and the death of the Grand Vizier Damad Ibrahim.

According to historical sources of the city of Valjevo, the heads of the murdered men were put on public display in the central square to serve as an example to those who might plot against the rule of the Janissaries.

The Janissaries' abuse of power, military ineffectiveness, resistance to reform, and the cost of salaries to 135,000 men, many of whom were not actually serving soldiers, had all become intolerable.

[61] The military music of the Janissaries was noted for its powerful percussion and shrill winds combining kös (giant timpani), davul (bass drum), zurna (a loud shawm), naffir, or boru (natural trumpet), çevgan bells, triangle (a borrowing from Europe), and cymbals (zil), among others.

In modern times, although the Janissary corps no longer exists as a professional fighting force, the tradition of Mehter music is carried on as a cultural and tourist attraction.