On 22 February 1821, Alexander Ypsilantis along with a small escort of five persons crossed the River Pruth, the boundary with Russia and the Danubian principalities (Moldavia and Wallachia) which belonged to the Ottoman Empire. In Moldavian territory the garrison of Prince Michael Soutsos was waiting for Ypsilantis and escorted him to Iasi. There, on 24 February he issued the proclamation 'Fight for Faith and Country', which is considered the official proclamation of the Greek Revolution. Two days later a religious ceremony was performed during which the flag of the revolution was blessed. On one was a phoenix, the main symbol of the Philiki Etaireia, and the phrase Reborn from my Ashes, and on the other were Constantin and Helen, founders of Constantinople and of the Byzantine Empire, figures equal to Apostles, the cross and the phrase In this our Victory. During his short stay in Iasi the first preparations were made for the concentration of money and the formation of an army of Balkan volunteers, who flocked there while more letters were issued, one of which was the one addressed to the Russian Emperor.

Ypsilantis left Iasi on 1 March, crossed Moldavia, passed on to Walachia and towards the end of the month he was out of Bucharest where the armed forces of Georgakis Olympios had already arrived. The small Ottoman garrisons could not prevent his advance. Nevertheless, problems had already appeared. The military preparations were inadequate. The army was formed on the way and depended on volunteers, and there were many unarmed volunteers and others inadequately armed. Most of the Greeks of these regions seemed hesitant in providing active and substantial support while the local populations were often hostile, because of the looting and plundering by parts Ypsilantis' army. In addition, there was no sign of the Serbs revolting, communication with Ali Pasha was not possible and only Vladimirescu, the leader of the agricultural movement in Walachia, who was also heading to Bucharest at the same period, could be seen as an ally.

At the end of March the perspective of a positive outcome was weakening, especially after the excommunication of Ypsilantis by the Patriarch and the condemnation of the uprising by the Emperor of Russia, who would now allow Ottoman troops into the principalities. Indeed, a great number of Ottoman troops were concentrated here until the end of April and were prepared to confront the army of Ypsilantis. In the same period Vladimirescu was in contact with the Ottomans and was more interested in negotiating with them than entering into conflict. Furthermore, in Moldavia the nobles (boyards), turned against Ypsilantis when they realized that Russia was not supporting his movement and asked the contribution of the Ottomans. This obliged Michael Soutsos and many other Greeks to seek refuge in the neighbouring region of Bessarabia.