1255

Events

February 25 - Battle of Montebruno: Guelph forces under Thomas II of Savoy invade the Ghibelline territory of Asti, but he is defeated by the Astigiani army, led by William VII, at Garzigliana. Thomas retreats and takes refuge in Turin; however, he is later captured by the Ghibellines.
May - William of Rubruck from Constantinople returns to Cyprus from his missionary journey to convert the Mongols of central and eastern Asia; his efforts have been unsuccessful.
Emperor Theodore II Laskaris, who is in exile in the Empire of Nicaea, conducts a military campaign to recover Thrace from the Bulgarians.
King Afonso III of Portugal moves his residence and royal court from Lisbon to Coimbra, which becomes the capital of Portugal.
The Teutonic Knights in Prussia found Königsberg and name it in honour of King Ottokar II of Bohemia.
The lands of the House of Nassau are divided between the brothers Walram II and Otto I, not to be reunited until 1806.

June - Battle of Bryn Derwin: Llywelyn ap Gruffudd defeats his two brothers Dafydd ap Gruffydd and Owain Goch ap Gruffydd, to become sole ruler of northern Wales. Dafydd and Owain are both imprisoned.
August - Following the death of Little Saint Hugh, in an instance of blood libel, eighteen Jews of Lincoln, are tortured and executed by royal command on suspicion of being involved in the boy's murder.
A survey of royal privileges is conducted, which is included in the Hundred Rolls, a census seen as a follow-up to the Domesday Book. The Hundred Rolls is later completed with two larger surveys, in 1274/75 and 1279/80.

Orlando Bonsignori, an Italian minor merchant, forms a consortium called the Gran Tavola, which becomes the most powerful bank in western Europe. He becomes the exclusive banker for the deposits of the income of the Papal States.