In 1814, a secret organization called the Filiki Eteria was founded with the aim of liberating Greece. The Filiki Eteria planned to launch revolts in the Peloponnese, the Danubian Principalities, and capital with its surrounding areas. The first of these revolts began on 6 March 1821 in the Danubian Principalities which was put down by the Ottomans. On 17 March 1821, the Maniots declared war which was the start of revolutionary actions from other controlled states. In October 1821, Theodoros Kolokotronis had captured Tripolitsa, followed by other revolts in Crete, Macedonia, and Central Greece. Tensions soon developed among different Greek factions, leading to two consecutive civil wars. Mehmet Ali of Egypt agreed to send his son Ibrahim Pasha to Greece with an army to suppress the revolt in return for territorial gain. By the end of 1825, most of the Peloponnese was under Egyptian control, and the city of Missolonghi was put under siege and fell in April 1826. Ibrahim had succeeded in suppressing most of the revolt in the Peloponnese and Athens had been retaken. Russia, Britain and France decided to intervene in the conflict and each nation sent a navy to Greece. Following news that combined Ottoman–Egyptian fleets were going to attack the Greek island of Hydra, the allied fleet intercepted the Ottoman–Egyptian fleet in the battle of Navarino. Following a week-long standoff, a battle began which resulted in the destruction of the Ottoman–Egyptian fleet. With the help of a French expeditionary force proceeded to the captured part of Central Greece by 1828.