Hasan, together with his friend, Grand Vizier Koca Yusuf Pasha, both important figures in the politics of the Ottoman Empire, convinced the Sultan Abdul Hamid I to name Mavrogenes prince of Wallachia on 6 April 1786.

[5] He also attempted to erect stakes on all major crossroads, to show the people what would happen to them if they engaged in theft or murder, or if they failed to attend church services.

[7] Mavrogenes often extorted money from the boyars,[1] for which he cited as pretext his recurring dreams, in which he claimed to have been commanded random killings or banishments, effects which he was allowed to avert only if paid a certain sum.

Severin was soon freed, after the intervention of Georg Ignaz, Freiherr von Metzburg, the Habsburg consul, who described Mavrogenes as acting maniacally and being terrified by the prospect of being at war.

[9] As the city of Bucharest was spread over a large area and lacked any kind of fortifications, Mavrogenes decided to build some, including the digging of a moat from Cotroceni to Oborul Vechi, as well as reinforcing the walls of inns and monasteries (which were thus turned into crude fortresses).

[10] During that period, Mavrogenes used the services of Perdicari, an astrologer whom he trusted, and used both the predictions and his dreams for decisions in time of war, such as attacking the city of Kronstadt (present-day Braşov).

[11] On 21 November a Habsburg army of 20,000 men, located in the Banat and led by Prince Josias of Coburg, started pressuring the Wallachian border and soon occupied fortified spots such as the Tismana and Sinaia monasteries;[1] nevertheless, Mavrogenes continued to dismiss evidence of a Habsburg-Russian alliance.

Most Wallachians welcomed Prince Coburg's army,[17] and the local boyars accepted a document which basically annexed Wallachia, while keeping autonomy to the same level as within the Ottoman Empire.

[17] In June 1790, Mavrogenes, joined by a new Ottoman invading force, occupied the village of Calafat, but, after being attacked and defeated by the Habsburg troops, retreated and, all alone, crossed the Danube in a small boat.

The Romanian radical and historian Nicolae Bălcescu considered him an "original and fantastic man, despising the aristocracy, but having pity of the low-ranking and poor people".