Castilian Civil War (1366)

Timeline

1. 1366Montiel · CastilePeter I and Henry of Trastámara openly broke with each other over the succession and long-standing court grievances. In March 1366, Henry proclaimed himself King of Castile near Montiel, claiming that Peter was tyrannical and unworthy of the throne; the civil war thus began.
2. 1366Aragon–Castile frontier · CastileWith the tacit approval of French King Charles V, Henry entered Castile from Aragon at the head of the Free Companies commanded by Bertrand du Guesclin. Using rapid maneuver and plunder tactics, the companies shattered Peter's defenses in succession, quickly internationalizing the civil war and entangling it with the Hundred Years' War.
3. 1366La Coruña · CastileFacing the offensive of Henry and the companies, Peter abandoned the central heartland after defeats in several places and retreated to the Galician port of La Coruña. There he reorganized his remaining forces and sent envoys to Aquitaine to request aid from Edward, the Black Prince of England, setting the stage for the Battle of Nájera in 1367.
4. 1366Burgos · CastileIn September 1366, Henry entered Burgos, Castile's traditional seat of power, and was formally crowned King of Castile with the support of clergy and nobles. Although Peter remained in exile, Henry now controlled most of the kingdom, and the civil war entered a new phase of Peter's counteroffensive and deep foreign intervention.