1183: On September 24, Andronicus I Comnenus has his nephew Alexius II Comnenus strangled. 1184: On March 24, Queen Tamar, King of Georgia, accedes to the throne as sole ruler after reigning with her father, George III, for six years. 1184: Diet of Pentecost organised by Emperor Frederick I in Mainz. 1185: The Uprising of Asen and Peter against the Byzantine Empire leads to the restoration of the Bulgarian Empire. 1185: Andronicus I Comnenus is deposed and, on September 12, executed as a result of the Norman massacre of the Greeks of Thessalonika. 1185: The cathedral school (Katedralskolan) in Lund, Sweden, is founded. The school is the oldest in northern Europe, and one of the oldest in all of Europe. 1185: Beginning in this year the Kamakura shogunate deprives the emperor of Japan of political power. 1186: On January 27, the future Holy Roman Emperor Henry VI marries Constance of Sicily, the heiress to the Sicilian throne. 1187: On July 4, in the Battle of Hattin, Saladin defeats the king of Jerusalem. 1187: In August, the Swedish royal and commercial center Sigtuna is attacked by raiders from Karelia, Couronia and/or Estonia. 1188: The Riah were introduced into the Habt and south of Tetouan by the Almohad caliph, Abu Yusuf Yaqub al-Mansur, and Jochem and Acem were introduced in Tamesna. 1189: On September 3, Richard I is crowned King of England at Westminster. 1189: On November 11, William II of Sicily dies and is succeeded by his illegitimate cousin Tancred, Count of Lecce instead of Constance. 1189–1192: The Third Crusade is an attempt by European leaders to wrest the Holy Land from Saladin. 1190-1200 1190: On June 10, Emperor Frederick Barbarossa drowns in the River Salef, leaving the Crusader army under the command of the rivals Philip II of France and Richard I of England, which ultimately leads to the dissolution of the army. 1191: Holy Roman Emperor Henry VI attacked Kingdom of Sicily from May to August but fails and withdraws, with Empress Constance captured (released 1192). 1191: On September 7, Saladin is defeated by Richard I of England at the Battle of Arsuf. 1192: In April, Isabella I begins her reign as Christian Queen of the Kingdom of Jerusalem 1192: In the Battle of Jaffa, King Richard the Lionheart defeats Saladin. 1192: In June, the Treaty of Ramla is signed by Saladin and Richard Lionheart. Under the terms of