451: Battle of the Catalaunian Plains: Roman and Visigoths forces defeat Attila the Hun in north east France, halting Hun invasion of Roman Gaul (exact date disputed)

1789: French Revolution: The Third Estate of the French Estates-General swears the Tennis Court Oath at the Palace of Versailles, swearing not to disband until a new constitution is formed

1840: American inventor Samuel Morse patents his telegraph

1895: 1st female PhD from an American University, earned by Caroline Willard Baldwin (in Science) at Cornell University

2020: Highest-ever temperature recorded in the Arctic circle, 38C (100F) in Verkhoyansk, Siberia

Source: Onthisday.com