Greek War of Independence: Traditional date of the start of the Greek War of Independence. The war had actually begun on 23 February 1821 (Julian calendar).

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.

February 23 is the 54th day of the year in the Gregorian calendar; 311 days remain until the end of the year.

The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year. The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Amazigh people. For a quick calculation, between 1901 and 2099 the much more common Gregorian date equals the Julian date plus 13 days.