Castilian Civil War

The First Castilian Civil War
Part of the Hundred Years' War

Battle of Nájera, from a fifteenth-century manuscript, the English and Pedro are on the left while the French and Henry are on the right.
Date1351–1369
Location
Result Victory for Henry of Trastámara
Belligerents
Forces of Henry of Trastámara
Kingdom of France
Crown of Aragon
Forces of Peter of Castile
Kingdom of England
Kingdom of Navarre
Kingdom of Majorca
Emirate of Granada
Duchy of Aquitaine
Others
Elite European mercenaries
Commanders and leaders
Henry of Trastámara
Bertrand du Guesclin
Peter of Castile 
Edward, the Black Prince

The Castilian Civil War was a war of succession over the Crown 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.