Reconquest
After his false start at uniting Aragon with the Kingdom of Navarre through a scheme of mutual adoption, James turned to the south and the Mediterranean Sea, where he conquered Majorca on 31 December in 1229 and the rest of the Balearic Islands; Minorca 1232; Ibiza 1235). Valencia capitulated to Aragonese rule on 28 September 1238 following an extensive campaign which included the Siege of Burriana and the decisive Battle of the Puig where the Aragonese commander, Bernardo Guillermo de Entenza who was also the king's cousin, died from wounds received in action. Chroniclers say he used gunpowder in the siege of Museros castle.
During his remaining two decades after Corbeil, James warred with the Moors in Murcia, on behalf of his son-in-law Alfonso X of Castile. On 26 March 1244, the two monarchs signed the Treaty of Almizra to determine the zones of their expansion into Andalusia so as to prevent squabbling between them. Specifically, it defined the borders of the newly-created Kingdom of Valencia. James signed it on that date, but Alfonso did not affirm it until much later. According to the treaty, all lands south of a line from Biar to Villajoyosa through Busot were reserved for Castile.
Read more about this topic: James I Of Aragon