Year 1231 (MCCXXXI) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events By place Europe Emperor Frederick II promulgates the Constitutions of Melfi (Liber Augustalis), a collection of laws for Sicily, as well as the Edict of Salerno, regulating the exercise of medicine and separating the professions of physician and apothecary, and requiring medical schools to practice dissection. Castillian forces under King Ferdinand III (the Saint) re-conquer the city of Quesada. Battle of Jerez: Ferdinand III defeats Emir Ibn Hud of the Taifa of Murcia. England Spring – Hubert de Burgh becomes a powerful lord in the Welsh Marches, controlling the castles Cardigan and Carmarthen. He begins to threaten the local Welsh leaders, Llywelyn the Great launches a campaign against Norman lordship in Wales. August 13 – King Henry III orders the sheriffs of Hampshire, Dorsetshire and Wiltshire to give Simon de Montfort the possession of the lands of his father, Simon de Montfort (the Elder). December – Henry III ends his Welsh campaign and makes peace with Llywelyn the Great. The University of Cambridge is granted a royal charter by Henry III. Levant Autumn – Frederick II appoints Marshal Richard Filangieri as his imperial legate, and sends an expeditionary army of mostly Lombards for the defense of Jerusalem. He gathers some 600 knights, 100 "sergeants-at-arms", 700 armed infantrymen, and 3,000 marines. The army is supported by 32 war-galleys. War of the Lombards: Richard Filangieri sails for Beirut, where the town is handed over to him. He occupies Sidon and Tyre – while other Lombard forces appear before Acre. At Acre, Filangieri summons a meeting of the High Court and shows letters from Frederick II appointing him as ambassador (baili). China April 9 – A huge fire breaks out at night in the southeast of Hangzhou during the Song Dynasty. Fighting the flames is difficult due to limited visibility. When the fires are extinguished, it is discovered that an entire district of the city (some 10,000 houses) has been consumed by the flames. Mongol Empire August – Ögedei Khan orders the invasion of Korea. A Mongol army crosses the Yalu River and quickly secures the surrender of the border town of Uiju. The Mongols are joined by Hong Bok-won, a Goryeo general, who takes their side with his subordinates numbering some 1500 families. Siege of Kuju: Mongol forces besiege the city