[8] Peter IV declared James III a disobedient vassal and occupied the Balearic Islands, Roussillon and Cerdanya in May 1344.

[1] Scholar Nancy Goldstone proposes that James most probably met with his future wife, Joanna I of Naples, who had come to Avignon to stand trial for her alleged involvement in the murder of her first husband, Andrew.

[12] James III supported Joanna I during the trial and she promised to lend the Neapolitan fleet to him to invade the Balearic Islands.

[14] The marriage proved unsuccessful; however, in January 1365 Joanna was found to be pregnant with James IV's child, but unfortunately in June she had a miscarriage, as was noted in a letter of condolence sent to her by Pope Urban V dated 19 July 1365.

Henry had launched a war against Peter IV of Aragon, and James hoped to take advantage of this to capture Roussillon and Cerdanya, the mainland portions of his father's realm.

However, John of Gaunt procured a truce between Castile and Aragon, and the full weight of the Aragonese forces fell upon James.

He willed his rights to Achaea to Joanna, who had ruled the remains of the Principality since 1373 by cession of her brother-in-law, Philip II of Taranto.