First Castilian Civil War

The First Castilian Civil War
Battle of Nájera, from a fifteenth-century manuscript, the English and Pedro are on the left.
Date 1351 - 1369 Location Crown of Castile Result Victory for Henry of Trastámara
Belligerents
Forces of Pedro of Castile Kingdom of England Kingdom of Navarre Kingdom of Granada	Forces of Henry of Trastámara Kingdom of France Crown of Aragon
Commanders and leaders
Pedro of Castile Edward, the Black Prince John of Gaunt James of Majorca	Henry of Trastámara Charles V of France Bertrand du Guesclin

The Castilian Civil War was a war of succession over the Kingdom of Castile that lasted from 1351 to 1369. The conflict started after the death of king Alfonso XI of Castile in March 1350. It became part of the larger conflict then raging between the Kingdom of England and the Kingdom of France: the Hundred Years' War. It was fought primarily in Castile and its coastal waters between the local and allied forces of the reigning king, Peter, and his illegitimate brother Henry of Trastámara over the right to the crown.

Peter was called by his supporters "The Just" and by his detractors "The Cruel". To the higher ranks of the nobility, he was a tyrant, forcing the royal will on hitherto free men. He had greatly extended the royal authority and had entered into a war with the Crown of Aragon (called "The War of the Two Peters").

His illegitimate brother Henry quickly obtained the support of not only the upper noblesse, but France, Aragon, and the Papacy. In 1366, he officially deposed his brother as king of Castile, León, Toledo, and Seville and had himself proclaimed king in the monastery of Las Huelgas.

In 1366, Henry, then living in France, assembled a large army, with both French and Aragonese components and English mercenaries, at Montpellier and invaded Castile with the support of the kings of France and Aragon (Charles V and Peter IV respectively). He successfully forced Peter to flee.

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