March – King Ferdinand III (the Saint) turns the independent Taifa of Murcia into a protectorate, and initiates the process of the colonization and Christianization of the region. He receives the submission of the Moors, under the terms of a peace agreement (the famous Treaty of Alcaraz).
Siege of Viterbo: Emperor Frederick II besieges Viterbo on request of the rebel citizens. The defenders are able to set fire to the siege towers and after signing a peace treaty, Frederick is persuaded to withdraw his army.[2]
Siege of Montségur: French forces (some 10,000 men) begin the siege of Château de Montségur to raze the stronghold held by the rebellious Cathars. The castle is defended by some 100 troops and 500 refugees.[3]
Spring – Henry III bestows the custody of Kenilworth Castle to Simon de Montfort. Simon's wife Eleanor, Henry's sister, already owned Odiham Castle (or King John's Castle) so Simon has two of the strongest fortresses in England under his control.