War of the Two Peters

The war resulted in Aragon gaining the upper hand, but it also devastated its economy that was already reeling from the effects of the Black Death.

Peter of Castile sought to claim the Kingdom of Valencia, which included parts of Murcia, Elche, Alicante, and Orihuela.

[1] A naval incident between the two powers had already caused tension: Catalan galleys, armed by Mossèn Francesc de Perellós, who had letters of marque from the Aragonese king, aided France against England, and also managed to capture two Genoese ships at Sanlúcar de Barrameda.

[2] In June 1362, Peter of Castile met with Charles II of Navarre at Soria, and mutual aid was promised.

With these negotiations complete, the Castilian king invaded Aragonese territory without officially declaring war, and the conflict commenced again.

The papal nuncio Jean de la Grange arranged the peace of Morvedre (Sagunt) (2 July 1363) between the two kings.

He was assailed by his illegitimate brother Henry of Trastámara at the head of a host of soldiers of fortune, including Bertrand du Guesclin and Hugh Calveley.

Peter abandoned the kingdom without daring to give battle, after retreating several times (first from Burgos, then from Toledo, and finally from Seville) in the face of the oncoming armies.

[4] Castilian troops and their Moorish allies invaded southern Valencia, which suffered low-level ravaging and political instability.

However, the war is believed to have led to the establishment of administrative and military forces that would ultimately result in a unified Castile and Aragon in the next century.