April 12240 – Shapur I becomes co-emperor of the Sasanian Empire with his father Ardashir I. 467 – Anthemius is elevated to Emperor of the Western Roman Empire. 627 – King Edwin of Northumbria is converted to Christianity by Paulinus, bishop of York. 1012 – Duke Oldřich of Bohemia deposes and blinds his brother Jaromír, who flees to Poland. 1204 – The Crusaders of the Fourth Crusade breach the walls of Constantinople and enter the city, which they completely occupy the following day.
August 27410 – The sacking of Rome by the Visigoths ends after three days. 1172 – Henry the Young King and Margaret of France are crowned junior king and queen of England. 1232 – Shikken Hojo Yasutoki of the Kamakura shogunate promulgates the Goseibai Shikimoku, the first Japanese legal code governing the samurai class. 1557 – The Battle of St. Quentin results in Emmanuel Philibert becoming Duke of Savoy. 1593 – Pierre Barrière failed an attempt to assassinate Henry IV of France.
January 23393 – Roman emperor Theodosius I proclaims his eight-year-old son Honorius co-emperor. 971 – Using crossbows, Song dynasty troops soundly defeat a war elephant corps of the Southern Han at Shao. 1264 – In the conflict between King Henry III of England and his rebellious barons led by Simon de Montfort, King Louis IX of France issues the Mise of Amiens, a one-sided decision in favour of Henry that later leads to the Second Barons' War.
July 19AD 64 – The Great Fire of Rome causes widespread devastation and rages on for six days, destroying half of the city. 484 – Leontius, Roman usurper, is crowned Eastern emperor at Tarsus (modern Turkey). He is recognized in Antioch and makes it his capital. 711 – Umayyad conquest of Hispania: Battle of Guadalete: Umayyad forces under Tariq ibn Ziyad defeat the Visigoths led by King Roderic. 939 – Battle of Simancas: King Ramiro II of León defeats the Moorish army under Caliph Abd-al-Rahman III near the city of Simancas.
May 271096 – Count Emicho enters Mainz, where his followers massacre Jewish citizens. At least 600 Jews are killed. 1120 – Richard III of Capua is anointed as Prince two weeks before his untimely death. 1153 – Malcolm IV becomes King of Scotland. 1199 – John is crowned King of England. 1257 – Richard of Cornwall, and his wife, Sanchia of Provence, are crowned King and Queen of the Germans at Aachen Cathedral. 1644 – Manchu regent Dorgon defeats rebel leader Li Zicheng of the Shun dynasty at the Battle of Shanhai Pass, allowing the Manchus to enter and conquer the capital city of Beijing.
February 26747 BC – According to Ptolemy, the epoch (origin) of the Nabonassar Era began at noon on this date. Historians use this to establish the modern BC chronology for dating historic events. 364 – Valentinian I is proclaimed Roman emperor. 1266 – Battle of Benevento: An army led by Charles, Count of Anjou, defeats a combined German and Sicilian force led by Manfred, King of Sicily. Manfred is killed in the battle and Pope Clement IV invests Charles as king of Sicily and Naples.
July 26657 – First Fitna: In the Battle of Siffin, troops led by Ali ibn Abu Talib clash with those led by Muawiyah I. 811 – Battle of Pliska: Byzantine Emperor Nikephoros I is killed and his heir Staurakios is seriously wounded. 920 – Rout of an alliance of Christian troops from Navarre and Léon against the Muslims at the Battle of Valdejunquera. 1309 – The Holy Roman Emperor Henry VII is recognized King of the Romans by Pope Clement V. 1509 – The Emperor Krishnadevaraya ascends to the throne, marking the beginning of the regeneration of the Vijayanagara Empire.
October 211096 – A Seljuk Turkish army successfully fights off the People's Crusade. 1097 – First Crusade: Crusaders led by Godfrey of Bouillon, Bohemund of Taranto, and Raymond IV, Count of Toulouse, begin the Siege of Antioch. 1392 – Japanese Emperor Go-Kameyama abdicates in favor of rival claimant Go-Komatsu. 1512 – Martin Luther joins the theological faculty of the University of Wittenberg. 1520 – João Álvares Fagundes discovers the islands of Saint Pierre and Miquelon, bestowing them their original name of "Islands of the 11,000 Virgins".
October 2897 – Roman emperor Nerva is forced by the Praetorian Guard to adopt general Marcus Ulpius Trajanus as his heir and successor. 306 – Maxentius is proclaimed Roman emperor. 312 – Constantine I defeats Maxentius, becoming the sole Roman emperor in the West. 969 – The Byzantine Empire recovers Antioch from Arab rule. 1344 – The lower town of Smyrna is captured by Crusaders in response to Aydınid piracy. 1420 – Beijing is officially designated the capital of the Ming dynasty when the Forbidden City is completed.
February 201339 – The Milanese army and the St. George's (San Giorgio) Mercenaries of Lodrisio Visconti clash in the Battle of Parabiago; Visconti is defeated. 1472 – Orkney and Shetland are pawned by Norway to Scotland in lieu of a dowry for Margaret of Denmark. 1521 – Juan Ponce de León sets out from Spain for Florida with about 200 prospective colonists. 1547 – Edward VI of England is crowned King of England at Westminster Abbey. 1685 – René-Robert Cavelier establishes Fort St. Louis at Matagorda Bay thus forming the basis for France's claim to Texas.
