Theobald II of Navarre Theobald II ( c . 1239 – December 4 , 1270 ) ( French : " Thibaud " or " Thibault " , Spanish : " Teobaldo " ) , called the Young , was Count of Champagne and Brie ( as Theobald V ) and King of Navarre from 1253 until his death . He was the eldest son of Theobald I and his third wife , Margaret of Bourbon , Queen of Navarre . He succeeded to his father ' s titles on his father ' s death when he was only fourteen years of age . His mother acted as regent with James I of Aragon until 1256 , when Theobald came of age . On 27 November , he affirmed the Fueros of Navarre , which limited his power by putting him under the counsel of a tutor from among the aristocracy . He could not make judgements without a council of twelve ( a jury ) of noblemen . Theobald was not content , however , to be so restricted in royal prerogative before his twenty - first birthday . He received the rites of unction and coronation from Pope Alexander IV in 1257 and 1259 respectively and tried to justify his divine right to rule , a concept foreign until that point in traditional Navarrese politics ( though see the reign of Sancho III ) . In order to counter the tendency to decentralisation , diminish the power of the nobility , and evade the control of the fueros on him , the king turned to the bourgeoisie . He exacted extraordinary taxes and imposts from them , but they supported him nevertheless because he granted them rights , prestige , and political clout . He extended the " fueros " of Pamplona to Lanz and Estella to Tiebas and Torralba Del Río . He founded Espinal in 1269 . He continued the power struggle with the bishop of Pamplona started during his father ' s reign . The former stood by his native Basque parishioners of the Navarreria borough , while Theobald championed the Saint Nicolas borough of Pamplona , made up of Occitans hailing from southern France . Eventually he tried to put an end to the fights between boroughs in 1266 , pushing an agreement among the councils of the three Pamplonese boroughs — not that it avoided ultimately the destructive war of the Navarreria in 1276 . In other affairs , Theobald continued the policies of his father . He improved the royal administration , of incomes and expenditures , and administered the first census . The count of 1266 indicated the presence of 150 , 000 inhabitants . Approximately 6 . 75 % of royal revenues were spent on a bureaucracy , 33 . 84 % on the military , and 59 . 6 % to the maintenance of the monarch and his household and duties . Theobald found support in Louis IX of France , who supported his fellow kings against their vassals with consistency . Theobald married Isabella , Louis ' s daughter , on 6 April 1255 . Theobald acted as an advisor of Louis and Louis as an arbiter in Navarre ' s internal problems . When the daughter , Berengaria , of Alfonso X of Castile was betrothed to Louis , eldest son and heir of King Louis , Castile ceded the use of the ports of Fuenterrabía and San Sebastián to Navarre on 1 January 1256 . In July 1270 , Theobald embarked with his father - in - law on the Eighth Crusade to Tunis . Louis died of dysentery at the siege . Theobald died childless at Trapani in Sicily while returning that same year . He was succeeded by his younger brother Henry III of Champagne . His wife Isabella returned home to France , were she died a few months later .