The year 1826 was marked by events that defined the course of the Struggle. The Saint Petersburg Protocol was signed by Great Britain and Russia in April 1826, providing for the intervention of the two countries between the revolutionary Greeks and the Sublime Porte with an aim to create an autonomous Greek State tributary to the Sultan. That same month, the fall of Missolonghi revived the philhellenic interest in the Greek Struggle throughout Europe and America. Also important were the developments in the field of war: Ibrahim, continuing his military campaign in the Peloponnese, attacked Mani but failed to conquer it, while Kutahi Pasha began the siege of the Acropolis in the framework of his campaign in Central Greece. In the end of that year, the victory of Karaiskakis in the battle of Arachova, which lasted from 14 to 23 November, restored hope for the Greeks.