Died in 1270

Feb 23 Isabelle of France (saint) the daughter of Louis VIII of France and Blanche of Castile. She was a younger sister of King Louis IX of France and of Alfonso, Count of Poitiers, and an older sister of King Charles I of Sicily. In 1256 she founded the Poor Clare Monastery of Longchamp in the part of the Forest of Rouvray now called the Bois de Boulogne, west of Paris. She is honored as a saint by the Franciscan Order
May 3 Béla IV of Hungary King of Hungary and Croatia between 1235 and 1270, and Duke of Styria from 1254 to 1258. Being the oldest son of King Andrew II, he was crowned upon the initiative of a group of influential noblemen in his father's lifetime in 1214. His father, who strongly opposed Béla's coronation, refused to give him a province to rule up until 1220. In this year, Béla was appointed Duke of Slavonia, also with jurisdiction in Croatia and Dalmatia. Around the same time, Béla married Maria, a daughter of Theodore I Laskaris, Emperor of Nicaea. From 1226, he governed Transylvania with the title Duke. He supported Christian missions among the pagan Cumans who dwelled in the plains to the east of his province. Some Cuman chieftains acknowledged his suzerainty and he adopted the title of King of Cumania in 1233. King Andrew died on 21 September 1235 and Béla succeeded him. He attempted to restore royal authority, which had diminished under his father. For this purpose, he revised his predecessors' land grants and reclaimed former royal estates, causing discontent among the noblemen and the prelates
Jun 24 Maria Laskarina a daughter of Theodore I Laskaris and his first wife Anna Angelina.
Jul 17 Margaret Marchioness of Namur the daughter of Peter II of Courtenay and Yolanda of Flanders.
Jul 18 Boniface of Savoy (bishop) a medieval Bishop of Belley in France and Archbishop of Canterbury in England. He was the son of Thomas, Count of Savoy, and owed his initial ecclesiastical posts to his father. Other members of his family were also clergymen, and a brother succeeded his father as count. One niece was married to King Henry III of England and another was married to King Louis IX of France. It was Henry who secured Boniface's election as Archbishop, and throughout his tenure of that office he spent much time on the continent. He clashed with his bishops, with his nephew-by-marriage, and with the papacy, but managed to eliminate the archiepiscopal debt which he had inherited on taking office. During Simon de Montfort's struggle with King Henry, Boniface initially helped Montfort's cause, but later supported the king. After his death in Savoy, his tomb became the object of a cult, and he was eventually beatified in 1839
Aug 3 John Tristan Count of Valois a French prince of the Capetian dynasty. He was jure uxoris Count of Nevers from 1265 to 1270, Count of Auxerre and Tonnerre and also Count of Valois and Crépy
Aug 25 Alphonso of Brienne the son of John of Brienne and Berengaria of León, born in Acre. He was the Grand Butler of France in 1258
Aug 25 Hugh XII of Lusignan de Lusignan, Hugh VII of La Marche or Hugh III of Angoulême or Hugues XII & VII & III de Lusignan. He succeeded his father Hugh XI as seigneur of Lusignan, Couhe, and Peyrat, Count of La Marche and Count of Angoulême in 1250
Aug 25 Louis IX of France a Capetian King of France who reigned from 1226 until his death. Louis was crowned in Reims at the age of 12, following the death of his father Louis VIII the Lion, although his mother, Blanche of Castile, ruled the kingdom until he reached majority. During Louis's minority, Blanche dealt with the opposition of rebellious vassals and put an end to the Albigensian crusade which had started 20 years earlier
Dec 4 Theobald II of Navarre Count of Champagne and Brie and King of Navarre from 1253 until his death.