{{Infobox military conflict | conflict = Battle of Nájera (Navarrete) | width = | partof = the Castilian Civil War | image = Battle najera froissart.jpg | image_size = 300px | alt = | caption = The Battle of Nájera from a fifteenth-century manuscript of Froissart's Chronicles. The English and Peter of Castile are on the left. | date = 3 April 1367 | place = Nájera | coordinates = | result = Victory for Peter I | combatant1 = Castilians supporting Peter Kingdom of England Duchy of Aquitaine Kingdom of Majorca Kingdom of Navarre Other Elite European mercenaries | combatant2 = Castilians supporting Henry Kingdom of France Crown of Aragon | commander1 = Peter of Castile Edward, the Black Prince Jean de Grailly Gaston de Foix John of Gaunt John Chandos Jean I d'Armagnac James IV of Majorca | commander2 = Henry of Trastámara Bertrand du Guesclin Alfonso of Ribagorza Tello of Castile | strength1 = Total: more than 10,000.6,000 Elite European mercenaries2,000 Aquitaine soldiers1,000 English soldiers800 Castilian soldiers500 English longbowmen300 Navarrese soldiersTroops from MajorcaHenry deserters and other Spanish followers of King Peter. | strength2 = Total: more than 4,500.2,500 Castilian soldiers1,000 Elite French mercenaries1,000 Aragonese soldiers | casualties1 = Unknown | casualties2 = Heavy losses }} The Battle of Nájera, also known as the Battle of Navarrete''', was fought on 3 April 1367 to the northeast of Nájera, in the province of La Rioja, Castile. It was an episode of the first Castilian Civil War which confronted King Peter of Castile with his half-brother Count Henry of Trastámara who aspired to the throne; the war involved Castile in the Hundred Years' War. Castilian naval power, far superior to that of France or England, encouraged the two polities to take sides in the civil war, to gain control over the Castilian fleet. King Peter of Castile was supported by England, Aquitaine, Majorca, Navarra and the best European mercenaries hired by the Black Prince. His rival, Count Henry, was aided by a majority of the nobility and the Christian military organizations in Castile. While neither the Kingdom of France nor the Crown of Aragon gave him official assistance, he had on his side many Aragonese Soldiers and the French free companies loyal to his lieutenant the Breton knight and French commander Bertrand du Guesclin. Although the battle ended with a resounding defeat for Henry, it had disastrous consequences for King