On This Day: March 30th

One of the most important battles of the Dominican War of Independence from Haiti takes place near the city of Santiago de los Caballeros.

Ether anesthesia is used for the first time, in an operation by the American surgeon Dr. Crawford Long.

The National Bank of Greece is founded in Athens.

The Florida Territory is created in the United States.

Physicist Augustin Fresnel reads a memoir on optical rotation to the French Academy of Sciences, reporting that when polarized light is "depolarized" by a Fresnel rhomb, its properties are preserved in any subsequent passage through an optically-rotating crystal or liquid.

Joachim Murat issues the Rimini Proclamation, among the earliest calls for Italian unification.

Guru Gobind Singh establishes the Khalsa in Anandpur Sahib, Punjab.

Edward I sacks Berwick-upon-Tweed, during armed conflict between Scotland and England.

The people of Sicily rebel against the Angevin king Charles I, in what becomes known as the Sicilian Vespers.

Avar-Byzantine wars: The Avars lift the siege at the Byzantine stronghold of Tomis. Their leader Bayan I retreats north of the Danube River after the Avaro-Slavic army is decimated by the plague.