'Event of Fortune' in Constantinople; Vaka-i Şerriyye, "Event of Malignity" in the Balkans) was the forced disbandment of the centuries-old Janissary Corps by Ottoman Sultan Mahmud II on 15 June 1826.

Janissaries began as an elite corps made up through the devşirme system of child slavery, by which young Christian boys, notably Serbs, Albanians, Bulgarians, Croats, Greeks, and Romanians were taken from the Balkans, circumcised, converted to Islam, and incorporated into the Ottoman army.

[7] However, by the early 17th century, the Janissary corps had ceased to function as an elite military force, and had become a privileged hereditary class, and their exemption from paying taxes made them highly unfavorable in the eyes of the rest of the population.

[8] Over time it became clear that for the empire to restore its position as a major power of Europe, it needed to replace the Janissary corps with a modern army.

Mahmud II then brought out the Holy Banner of the Islamic prophet Muhammad from inside the Sacred Trust, intending all true believers to gather beneath it and thus bolster opposition to the Janissaries.

A new modern corps, Asakir-i Mansure-i Muhammediye ("The Victorious Soldiers of Muhammad"), was established by Mahmud II to guard the Sultan and replace the Janissaries.

In particular, they incited Christians in the Balkans, inflaming existing hostility to their Muslim neighbors and strengthening armed resistance to the new Turkish armies sent from Constantinople.

[3] Immediately after the Janissaries had been disbanded, Mahmud II ordered the court chronicler, Mehmet Esad Efendi, to record the official version of events.