1122 – Pope Callixtus II and Holy Roman Emperor Henry V agree to the Concordat of Worms to put an end to the Investiture Controversy.
1338 – The Battle of Arnemuiden was the first naval battle of the Hundred Years’ War and the first naval battle using artillery, as the English ship Christofer had three cannon and one hand gun.
1409 – Battle of Kherlen, the second significant victory over Ming dynasty China by the Mongols since 1368.
1459 – Battle of Blore Heath, the first major battle of the English Wars of the Roses, is fought at Blore Heath in Staffordshire.
1568 – Spanish naval forces rout an English fleet, under the command of John Hawkins, at the Battle of San Juan de Ulúa near Veracruz.
1779 – American Revolution: John Paul Jones on board the USS Bonhomme Richard wins the Battle of Flamborough Head.
1780 – American Revolution: British Major John André is arrested as a spy by American soldiers exposing Benedict Arnold’s change of sides.
1803 – Second Anglo-Maratha War: Battle of Assaye between the British East India Company and the Maratha Empire in India.
1821 – Tripolitsa, Greece, is captured by Greek rebels during the Greek War of Independence.
1846 – Astronomers Urbain Jean Joseph Le Verrier, John Couch Adams and Johann Gottfried Galle collaborate on the discovery of Neptune.
1868 – Grito de Lares (“Lares Revolt”) occurs in Puerto Rico against Spanish rule.
1899 – American Asiatic Squadron destroys a Filipino battery at the Battle of Olongapo.
1905 – Norway and Sweden sign the “Karlstad treaty”, peacefully dissolving the Union between the two countries.
1911 – Pilot Earle Ovington makes the first official airmail delivery in America under the authority of the United States Post Office Department
1913 – Roland Garros of France becomes the first to fly in an airplane across the Mediterranean (from St. Raphael France to Bizerte, Tunisia).
1932 – The Kingdom of Hejaz and Nejd is renamed the Kingdom of Saudi Arabia.
1938 – Mobilization of the Czechoslovak army in response to the Munich Crisis.
1942 – World War II: The Matanikau action on Guadalcanal begins: U.S. Marines attack Japanese units along the Matanikau River.
1943 – World War II: The Nazi puppet state known as the Italian Social Republic is founded.
1950 – Korean War: The Battle of Hill 282: The first US friendly-fire incident on British military personnel since World War II occurs.
1973 – Juan Perón returns to power in Argentina.
1983 – Saint Kitts and Nevis joins the United Nations.
1983 – Gulf Air Flight 771 is destroyed by a bomb, killing all 117 people on board.
1999 – NASA announces that it has lost contact with the Mars Climate Orbiter.