On This Day: October 15

Edgar the Ætheling is proclaimed King of England, but is never crowned. He reigns until 10 December 1066.

Battle of the Rhyndacus: The Latin emperor Henry of Flanders defeats the Nicaean emperor Theodore I Laskaris.

The Siege of Vienna ends as the Austrians rout the invading Turks, turning the tide against almost a century of unchecked conquest throughout eastern and central Europe by the Ottoman Empire.

Pope Gregory XIII implements the Gregorian calendar. In Italy, Poland, Portugal, and Spain, October 4 of this year is followed directly by October 15.

Edward Gibbon observes a group of friars singing in the ruined Temple of Jupiter in Rome, which inspires him to begin work on The History of the Decline and Fall of the Roman Empire.

The Montgolfier brothers' hot air balloon (tethered) makes the first human ascent, piloted by Jean-François Pilâtre de Rozier.

Queen Marie Antoinette of France is tried and convicted in a swift, pre-determined trial in the Palais de Justice, Paris, and condemned to death the following day.

Emperor Napoleon I begins his exile on Saint Helena in the Atlantic Ocean.

American Civil War: The H. L. Hunley, the first submarine to sink a ship, sinks during a test, killing its inventor, Horace L. Hunley.

American Civil War: The Battle of Glasgow is fought, resulting in the surrender of Glasgow, Missouri and its Union garrison, to the Confederacy.