The Greek War of Independence, also known as the Greek Revolution, was a successful war of independence waged by the Greek revolutionaries between 1821 and 1832 against the Ottoman Empire. The Greeks were later assisted by the Russian Empire, Great Britain, the Kingdom of France, and several other European powers, while the Ottomans were aided by their vassals the eyalets of Egypt, Algeria, and Tripolitania, and the Beylik of Tunis. Even several decades before the fall of Constantinople to the Ottoman Emp8ire in 1453, most of Greece had come under Ottoman rule. During this time, there were several revolt attempts by Greeks to gain independence from Ottoman control. In 1814, a secret organization called the Filike Eteria was founded with the aim of liberating Greece. The Filiki Eteria planned to launch revolts in the Peloponnese, the Danubian Principalities, and in Constantinople and its surrounding areas. The first of these revolts began on March 6, 1821, in the Danubian Principalities, but it was soon put down by the Ottomans. The events in the north urged the Greeks in the Peloponnese into action and on March 17, 1821, the Maniots declared war on the Ottomans. This declaration was the start of a spring of revolutionary actions from other controlled states against the Ottoman Empire. By the end of the month, the Peloponnese was in open revolt against the Turks and by October 1821, the Greeks had captured Triplitsa. The Peloponnesian revolt was quickly followed by revolts in Crete, Macedonia, and Central Greece, which would soon be suppressed. Meanwhile, the makeshift Greek navy was achieving success against the Ottoman navy in the Aegean Sea and prevented Ottoman reinforcements from arriving by sea. Tensions soon developed among different Greek factions, leading to two consecutive civil wars. In the meantime, the Ottoman Sultan negotiated with Mehmet Ali of Egypt, who agreed to send his son to Greece with an army to suppress the revolt in return for territorial gain. They landed in the Peloponnese in February 1825 and had immediate success; by the end of 1825, most of the Peloponnese was under Egyptian control, and the city of Missolonghi fell in April 1826 after a year-long siege by the Turks. With defeat Athens had been retaken. Following hears of negotiation, three Great Powers -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 at Navarino. The battle began after a tense week-long standoff, ending in the destruction of the Ottoman-Egyptian fleet. By 1828, the Egyptian army withdrew under pressure of a French expeditionary force to which the Ottoman garrisons in the Peloponnese then surrendered, while the Greeks proceeded to the Ottoman-controlled part of central Greece. As a result of years of negotiation, Greece was finally recognized as an independent nation in the Treaty of Constantinople of May 1832. The Revolution is celebrated by the modern Greek state as a national day on March 25.