15th day events in history

January 15, 69 Otho seizes power in Rome, proclaiming himself Emperor of Rome, but rules for only three months before committing suicide
March 15, 221 Liu Bei, a Chinese warlord and member of the Han royal house, declares himself emperor of Shu-Han and claims his legitimate succession to the Han Dynasty
March 15, 280 Sun Hao of Eastern Wu surrenders to Sima Yan which began the Jin Dynasty
March 15, 351 Constantius II elevates his cousin Gallus to Caesar, and puts him in charge of the Eastern part of the Roman Empire
May 15, 392 Emperor Valentinian II is assassinated while advancing into Gaul against the Frankish usurper Arbogast. He is found hanging in his residence at Vienne
December 15, 533 Vandalic War: Byzantine general Belisarius defeats the Vandals, commanded by King Gelimer, at the Battle of Tricamarum
November 15, 565 Justin II succeeds his uncle Justinian I as emperor of the Byzantine Empire
May 15, 589 King Authari marries Theodelinda, daughter of the Bavarian duke Garibald I. A Catholic, she has great influence among the Lombard nobility
February 15, 590 Khosrau II is crowned king of Persia
August 15, 636 Arab–Byzantine wars: The Battle of Yarmouk between Byzantine Empire and Rashidun Caliphate begins
November 15, 655 Battle of the Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria
September 15, 668 Eastern Roman Emperor Constans II is assassinated in his bath at Syracuse, Italy
December 15, 687 Pope Sergius I is elected
February 15, 706 Byzantine emperor Justinian II has his predecessors Leontios and Tiberios III publicly executed in the Hippodrome of Constantinople
August 15, 717 Arab–Byzantine wars: Maslamah ibn Abd al-Malik begins the Second Arab Siege of Constantinople, which will last for nearly a year
August 15, 718 Arab–Byzantine wars: Raising of the Second Arab Siege of Constantinople
August 15, 747 Carloman, mayor of the palace of Austrasia, renounces his position as majordomo and retires to a monastery near Rome. His brother Pepin the Short becomes the sole ruler (de facto) of the Frankish Kingdom
July 15, 756 An Lushan Rebellion: Emperor Xuanzong of Tang is ordered by his Imperial Guards to execute chancellor ] by forcing him to commit suicide or face a mutiny. He permits his consort Yang Guifei to be strangled by his chief eunuch. General An Lushan has other members of the emperor's family killed
April 15, 769 The Lateran Council condemned the Council of Hieria and anathematized its iconoclastic rulings
August 15, 778 The Battle of Roncevaux Pass, at which Roland is killed
September 15, 921 At Tetin, Saint Ludmila is murdered at the command of her daughter-in-law
June 15, 923 Battle of Soissons: King Robert I of France is killed and King Charles the Simple is arrested by the supporters of Duke Rudolph of Burgundy
August 15, 927 The Saracens conquer and destroy Taranto
March 15, 933 After a ten-year truce, German King Henry I defeats a Hungarian army at the Battle of Riade near the Unstrut river
August 15, 982 Holy Roman Emperor Otto II is defeated by the Saracens in the Battle of Capo Colonna, in Calabria
September 15, 994 Major Fatimid victory over the Byzantine Empire at the Battle of the Orontes
August 15, 1018 Byzantine general Eustathios Daphnomeles blinds and captures Ibatzes of Bulgaria by a ruse, thereby ending Bulgarian resistance against Emperor Basil II's conquest of Bulgaria
August 15, 1040 King Duncan I is killed in battle against his first cousin and rival Macbeth. The latter succeeds him as King of Scotland
August 15, 1057 King Macbeth is killed at the Battle of Lumphanan by the forces of Máel Coluim mac Donnchada
October 15, 1066 Edgar the Ætheling is proclaimed King of England, but is never crowned. Reigned until 10 December 1066
August 15, 1070 The Pavian-born Benedictine Lanfranc is appointed as the new Archbishop of Canterbury in England
April 15, 1071 Bari, the last Byzantine possession in southern Italy, is surrendered to Robert Guiscard
July 15, 1099 First Crusade: Christian soldiers take the Church of the Holy Sepulchre in Jerusalem after the final assault of a difficult siege
February 15, 1113 Pope Paschal II issues a bill sanctioning the establishment of the Order of Hospitallers
July 15, 1149 The reconstructed Church of the Holy Sepulchre is consecrated in Jerusalem
December 15, 1161 Jin–Song wars: Military officers conspire against Emperor Hailing of the Jin Dynasty after a military defeat at the Battle of Caishi, and assassinate the emperor at his camp
December 15, 1167 Sicilian Chancellor Stephen du Perche moves the royal court to Messina to prevent a rebellion
June 15, 1184 King Magnus V of Norway is killed at the Battle of Fimreite
August 15, 1185 The cave city of Vardzia is consecrated by Queen Tamar of Georgia
July 15, 1207 King John of England expels Canterbury monks for supporting Archbishop Stephen Langton
October 15, 1211 Battle of the Rhyndacus: The Latin emperor Henry of Flanders defeats the Nicaean emperor Theodore I Lascaris
June 15, 1215 King John of England puts his seal to the Magna Carta
June 15, 1219 Northern Crusades: Danish victory at the Battle of Lyndanisse (modern-day Tallinn) establishes the Danish Duchy of Estonia. According to legend, this battle also marks the first use of the Dannebrog, the world's first national flag still in use, as the national flag of Denmark
August 15, 1237 The Battle of the Puig takes place in the context of the Spanish Reconquista pitting the forces of the Taifa of Valencia against the Kingdom of Aragon. The battle resulted in an Aragonese victory
July 15, 1240 Swedish–Novgorodian Wars: A Novgorodian army led by Alexander Nevsky defeats the Swedes in the Battle of the Neva
June 15, 1246 With the death of Duke Frederick II, the Babenberg dynasty ends in Austria
August 15, 1248 The foundation stone of Cologne Cathedral, built to house the relics of the Three Wise Men, is laid. (Construction is eventually completed in 1880.)
May 15, 1252 Pope Innocent IV issues the papal bull ad extirpanda, which authorizes, but also limits, the torture of heretics in the Medieval Inquisition
December 15, 1256 Hulagu Khan captures and destroys the Hashshashin stronghold at Alamut Castle (in present-day Iran) as part of the Mongol offensive on Islamic southwest Asia
August 15, 1261 Michael VIII Palaiologos is crowned Byzantine emperor in Constantinople