1255

By place

Asia

• Hulagu Khan begins his campaign to destroy the remaining Muslim states in southwestern Asia, with the main targets being the Nizari Ismaili strongholds and the Abbasid Caliphate in Baghdad.

  Europe

• May - William of Rubruck from Constantinople returns to Cyprus, from his missionary journey to convert the Tatars of central and eastern Asia, his efforts having been unsuccessful.
• August - The final Cathar stronghold in southern France falls, eliminating their last refuge, since the Roman Catholic Church began the Albigensian Crusade to crush the sect in 1209.
• The death of Little Saint Hugh of Lincoln prompts the persecution of Jews in England, based on the blood libel.
• Lisbon becomes the capital of Portugal.
• A survey of royal privileges is conducted, which is included in the Hundred Rolls, an English census seen as a followup to the Domesday Book completed in 1086; the Hundred Rolls is later completed with two larger surveys, in 1274/1275 and 1279/1280.
• Königsberg is founded by the Teutonic Knights in Prussia, and named in honour of King Ottokar II of Bohemia.
• Theodore II Laskaris, Byzantine Emperor, conducts a military campaign to recover Thrace from the Bulgarians. He concludes the task successfully a year later, in 1256.
• The Duchy of Bavaria is split into Upper and Lower Bavaria.
• The lands of the House of Nassau are divided, not to be reunited until 1806.
• King Béla IV of Hungary grants Banská Bystrica the municipal rights of a royal town.

  By topic

Arts and culture

• The Gothic cathedral at Bourges, France, is completed.

  Markets

• At the death of Bernardo Bonsignori, his brother, Orlando, is left sole director of the largest banking firm in western Europe, the Gran Tavola of Siena.