During the war against the rebellious Serbian state, the Ottoman Empire tried to resolve the issue of Serbia in various ways, including diplomatic efforts, and the use of force. One of the letters, written on 13 July 1807, in the office of either Grand Vizier or another high-ranking official of Porta who had the vizier rank, indicated how the Ottoman authorities acted that year in order to conquer Serbia. The letter was critically arranged, along with the Serbian translation and transcription to the contemporary Turkish spelling. This resource contained information about an unsuccessful mediating mission of a Metropolitan of the Ecumenical Patriarchate, as well as on the decision to stop the uprising by force. Comparing it with other sources, it could be concluded that the Metropolitan was the Bishop of Ćustendil. As anticipated military measures were concerned, they were very cruel: enslavement of all vassals who abandoned him, looting and destroying their property. However, this proclamation could not be realized because in 1806 and 1807, Serbian uprising army won a series of victories over the Ottoman army. Then, Porta again turned to diplomatic means, but in 1813, the military solution was fully in accordance with the proclamations from this letter.