The Greek War of Independence, also known as the Greek Revolution or the Greek Revolution of 1821, was a successful war of independence by Greek revolutionaries against the Ottoman Empire between 1821 and 1829. In 1826, the Greeks were assisted by the British Empire, Kingdom of France, and the Russian Empire, while the Ottomans were aided by their vassals, especially by the Eyalet of Egypt. The war led to the formation of modern Greece, which would be expanded to its modern size in later years. The revolution is celebrated by Greeks around the world as independence day on 25 March.
All Greek territory, except the Ionian Islands, came under Ottoman rule in the 15th century, in the decades surrounding the Fall of Constantinople. During the following centuries, there were sporadic but unsuccessful Greek uprisings against Ottoman rule. In 1814, a secret organization called the Filiki Eteria (Society of Friends) was founded with the aim of liberating Greece. It planned to launch revolts in the Peloponnese, the Danubian Principalities, and Constantinople. The insurrection was planned for 25 March 1821, the Orthodox Christian Feast of the Annunciation. However, the plans were discovered by the Ottoman authorities, forcing it to start earlier.