TheWar of the Two Peters (Spanish:La Guerra de los Dos Pedros,Catalan:Guerra dels dos Peres), also known as theCastilian–Aragonese War of 1356–1369, was fought from 1356 to 1369 between the crowns ofCastile andAragon. The conflict was a struggle between two claimants to the throne of Castile,Peter of Castile andPeter IV of Aragon. The former Peter was supported by England and several English nobles led byEdward III and hisson, while the latter Peter was supported by France. The conflict also brought in the involvement of the kingdoms ofNavarre andPortugal. The war resulted in Aragon gaining the upper hand, but it also devastated its economy that was already reeling from the effects of theBlack Death.

At the beginning of the fourteenth century, Castile was suffering from unrest caused by itscivil war, which was fought between the local and allied forces of the reigning king, Peter of Castile, and his half-brotherHenry of Trastámara over the right to the crown.

Peter IV of Aragon supported Henry of Trastámara. Henry was also supported by the French commanderBertrand du Guesclin and his "free companies" of troops. Peter of Castile was supported by theEnglish. The War of the Two Peters can thus be considered an extension of the widerHundred Years' War as well as theCastilian Civil War.

Peter of Castile sought to claim theKingdom of Valencia, which included parts ofMurcia,Elche,Alicante, andOrihuela. Peter of Aragon wished to dominate theMediterranean in opposition to Castile and Castile's allyGenoa.^[1]

A naval incident between the two powers had already caused tension:Catalangalleys, armed by Mossèn Francesc de Perellós, who hadletters of marque from the Aragonese king, aided France against England, and also managed to capture twoGenoese ships atSanlúcar de Barrameda. Genoa was an ally of Castile. Peter of Castile, leading the Castilian fleet, caught up to Perellós atTavira but was unable to capture him.

The war lasted from 1356 to 1369, prolonged because Peter of Castile lost his throne to Henry of Trastámara. The war primarily took place on the border between Castile and Aragon, namely Aragonese border towns such asTeruel, which fell to the Castilians.

In 1357, Castile penetrated Aragon and conqueredTarazona on March 9; on May 8, they arranged a temporary truce.

At the beginning of 1361, the Castilians conquered the fortresses ofVerdejo,Torrijos,Alhama, and other places. However, thepeace of Terrer (sometimes called thepeace of Deza) was negotiated on 18 May 1361, in which all conquered places and castles were returned to their original lords.Bernardo de Cabrera, ambassador of the Aragonese king, negotiated the peace. Peter IV married his daughterConstance toFrederick III the Simple.^[2]

In June 1362, Peter of Castile met withCharles II of Navarre atSoria, and mutual aid was promised. Peter also contracted an alliance withEdward III of England and Edward's sonThe Black Prince.

With these negotiations complete, the Castilian king invaded Aragonese territory without officially declaring war, and the conflict commenced again. The Aragonese king was atPerpignan without troops, and thus caught off guard. The Castilians took the castles ofArize,Atece, Terrer,Moros,Cetina, andAlhama. Peter of Castile was unable to takeCalatayud, even though he attacked it with all types ofsiege machines. Without taking his conquests any further, he returned toSeville.

In 1363, Castile continued the war against Aragon, and again occupied Tarazona. Peter of Castile received reinforcements fromPortugal andNavarre. Meanwhile, the Aragonese king negotiated a treaty withFrance and a secret treaty with Henry II of Castile. Pedro of Castile then conqueredCariñena,Teruel,Segorbe,Morvedre,Almenara,Xiva, andBunyol.

ThepapalnuncioJean de la Grange arranged thepeace ofMorvedre (Sagunt) (2 July 1363) between the two kings. The peace was not ratified, however, and hostilities continued. The Castilians penetrated theKingdom of Valencia in 1363, and conqueredAlicante,Caudete,Elda,Gandia, and other places.

From 1365 to 1369, Peter of Castile was preoccupied with maintaining his position on the Castilian throne against Henry of Trastámara.

TheCastilian Civil War began in 1366 and Peter of Castile was dethroned. He was assailed by his illegitimate brotherHenry of Trastámara at the head of a host of soldiers of fortune, includingBertrand du Guesclin andHugh Calveley. Peter abandoned the kingdom without daring to give battle, after retreating several times (first fromBurgos, then fromToledo, and finally fromSeville) in the face of the oncoming armies. Peter fled with his treasury to Portugal, where he was coldly received by his uncle, KingPeter I of Portugal, and thence toGalicia, in northern Spain, where he ordered the murder of Suero, the archbishop ofSantiago, and thedean, Perálvarez. Both the Archbishop and the Dean were supporters of Henry.

Peter of Castile was overthrown in 1369. He was killed by Henry.^[3]

TheKingdom of Granada supported Peter of Castile in the War of the Two Peters.^[4] Castilian troops and theirMoorish allies invaded southernValencia, which suffered low-level ravaging and political instability. The Castilians unsuccessfully laid siege toOrihuela in 1364.^[5]

Castile recoveredcomarcas that had passed under Aragonese rule, such as the lordship ofMolina. A marriage was contracted betweenEleanor of Aragon, daughter of Peter IV of Aragon, andJohn I of Castile, the successor of Henry II of Castile.

The misery of the war was compounded by theBlack Death and other natural disasters, such asdrought and a plague oflocusts. These events ruined the Aragonese economy, leading to a decrease of the country’s population.^[6] TheCathedral of Tarazona was destroyed during the war and not rebuilt until much later.

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.^[7]

• 14th century in Aragon
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• Conflicts of the Hundred Years' War
• History of the Valencian Community
• Military history of Catalonia
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• 14th century in Castile
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