Until the end of April, when the Ottoman forces entered the principalities by crossing the Danube, only small skirmishes between the revolutionaries and the few Ottoman garrisons that were charged with police duties had occurred. The first large-scale conflict took place on 30 April at Galatsi, which was defended by military forces led by Athanasios Karpenisiotis. Galatsi is a town near the frontier of Moldavia and Walachia with Bessarabia (Russia). There, after a tough battle, the Ottomans captured the town making the small number of revolutionaries who had survived flee to Russian territory. The sturdy resistance of the men of Karpenissiotis resulted in the massacre of the locals and foreigners and the sack of the town.

At the same time disputes, rivalries, controversies and indiscipline made the situation even more difficult among the revolutionaries, and many started to desert. Under these conditions ALexander Ypsilantis decided to lead an offensive, the outcome of which he hoped would improve the situation. Thus, he concentrated in the region of Dragatsani the remaining armed forces. One of these was the Sacred Battalion which was composed of zealous young volunteers, but without military experience, from Odessa and other Greek communities of the Diaspora. However, indiscipline and the lack of coordination did not allow the application of his plan. The battle started one day earlier on the initiative of an individual officer, when the rest of the army had not yet been placed in the planned positions. Despite the sacrifice of the troops of the Sacred Battalion the outcome of the battle was tragic. The losses were enormous, almost complete while the panic provoked by the unexpected conflict resulted in a disorderly retreat and definitive dissolution of the army of Ypsilantis. Ypsilantis did not have time to reach the front, managed to pass the Austrian border in mid-June where, despite the initial agreement with the authorities, he was arrested and remained imprisoned until November 1827. A few months later, at the beginning of 1828, he died in Vienna.

After the destruction at Dragatsani only two small forces remained regrouped. One armed force led by Georgakis Olympios and Ioannis Pharmakis moved northwards to Moldavia, constantly giving hard and desperate battles. Their aim was to pass into Russian Bessarabia and from there to move with ships to the Peloponnese. Finally, after marching two and a half months through moutainous regions and after many battles in which the force of the revolutionaries was gradually crushed by its persecutors, they were trapped in the Sekou Monastery in northern Moldavia near the border with Austria. There, after a siege of more than two weeks during which G. Olympios and G. Pharmakis were killed, the few remaining revolutionaries of the army surrendered and suffered a tormenting death. The second force numbered about 250 armed men and its leader was the brother of Theodore Kolokotronis, Ioannis, who followed a different course from that of Olympios and Pharmakis. He moved southwards and crossing the Balkans tried to reach the Peloponnese. This reckless venture was crowned with success. Ioannis Kolokotronis reached the Peloponnese in August with about one hundred men and took part in the siege of Tripolitza, whose leader was his brother Theodoros.