For broader historical context, see 13th century.

Events

Europe

Western Europe

• August - The final Cathar stronghold in southern France falls, eliminating the last refuge of the heretical Cathars after the Roman Catholic Church engaged in a program to crush the sect, starting in 1209 with the Albigensian Crusade.
• The death of Little Saint Hugh of Lincoln prompts persecution of Jews in England on accusations of blood libel.
• The Portuguese capital is moved to Lisbon.
• The Gothic cathedral at Bourges, France, is completed. It is now a UNESCO World Heritage Site.

Central and eastern 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.
• Königsberg (now Kaliningrad) is founded in Prussia.
• Theodore II Lascaris, Byzantine Emperor (in exile in the Empire of Nicaea), 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 German state of Nassau is divided, not to be reunited until 1806.

Asia

• Hulagu Khan is dispatched by his brother Möngke Khan to destroy the remaining Muslim states in southwestern Asia.

Births

• July - Albert I of Germany, Holy Roman Emperor (d. 1308)
• Adolf of Nassau-Weilburg, King of the Romans (d. 1298)
• Duccio di Buoninsegna, Sienese painter (d. 1319)
• Grand Prince Andrei III of Russia (d. 1304)
• William de Ros, 2nd Baron de Ros, claimant to the crown of Scotland (d. 1317)

Deaths

• May 1 - Walter de Gray, English prelate and statesman.
• August - Little Saint Hugh of Lincoln
• Batu Khan, Mongol ruler and founder of the Blue Horde.
• Thomas of Celaeno, author of Dies Irae.
• Sundiata Keita, semi-historical hero and founder of the Mali Empire.

See also

• List of state leaders in 1255