a dyke to be constructed. After the camp is repaired, a serious epidemic strikes the Crusader forces. The victims suffer from a high fever, and at least a sixth of the soldiers die. During the severe winter, the survivors are left enfeebled and depressed. Mongol Empire Spring – Genghis Khan dispatches a Mongolian army (some 20,000 cavalry) under Jebe, to deal with the Qara Khitai (or Western Liao) threat. Meanwhile, he sends Subutai with another army on a simultaneous campaign against the Merkits. Jebe defeats a force of 30,000 men led by Prince Kuchlug at the Khitan capital Balasagun. Kuchlug flees south to modern Afghanistan, but is captured by hunters – who hands him over to the Mongols. After Kuchlug is beheaded and paraded through the cities of his new domains, Genghis annexes the entire Khitai empire under Mongol rule. Jochi, eldest son of Genghis Khan, leads a successful campaign against the Kyrgyz. Meanwhile, Genghis sends a caravan with precious gifts to Muhammad II, ruler (shah) of the Khwarazmian Empire, hoping to establish trade relations. However, Inalchuq, Khwarazmian governor of Otrar, attacks the caravan, claiming that the caravan contains spies. Genghis then sends a second group of three ambassadors to Muhammad to demand the merchants be set free. Muhammad refuses, and the merchants along with one of the ambassadors are executed. England March 11 – Treaty of Worcester: King Henry III writes to the Welsh ruler Llywelyn the Great and promises safe-conduct if they meet at Worcester. A peace treaty is signed, which confirms Llywelyn's ownership of Wales. In return, Llywelyn agrees to pay homage to Henry and to return those castles that he has captured during his recent conquests. Europe June 25 – Siege of Toulouse: During a counter-assault, Simon de Montfort is killed by a stone from one of the defender's siege engines. The leadership of the Albigensian Crusade falls to Simon's son Amaury de Montfort, who lifts the siege a month later. Raymond VI is restored as count of Toulouse after a popular rebellion. July – In order to facilitate the movement of Reconquista, Pope Honorius III reverses Innocent III’s earlier judgement, and declares King Ferdinand III (the Saint) legitimate heir to the Kingdom of León. Ivan Asen II becomes ruler (tsar) of the Bulgarian Empire, during his reign he will add Epirus, as well as parts of Albania and Macedonia to his realm. Levant August 31