The Civil War Among Ferdinand I’s Sons and the Rise of Sancho II (1065–1072 CE)

The Kingdoms of Castile, León, and Galicia had once been united under King Ferdinand I of León, known as "The Great." However, his division of the realm among his children led to years of dynastic warfare among his sons.

Ferdinand’s Succession Plan and Its Consequences

If Ferdinand I had followed Navarrese succession customs, his eldest son, Sancho of Castile, would have inherited either all or the majority of the kingdom. However, the Leónese nobility, considering themselves the true heirs of the ancient Visigothic kingdom, refused to accept Castilian rule. At this time, Castile had only recently transitioned from a frontier county of León into a full-fledged kingdom.

Ferdinand ultimately divided his realm:

• Alfonso VI was granted León.
• García II received Galicia.
• Sancho II inherited Castile.
• His daughters, Urraca and Elvira, were granted the towns of Zamora and Toro.

In addition, each brother was assigned a sphere of influence over different Taifa states.

The Breakdown of the Partition and the First Conflicts (1068–1071)

The division soon collapsed as the brothers turned on one another:

• In 1068, Alfonso VI invaded the Galician client Taifa of Badajoz, extorting tribute, violating the agreed division.
• In response, Sancho II attacked Alfonso, defeating him at the Battle of Llantada (1068 CE), though he failed to overthrow him.
• By 1071, Sancho and Alfonso joined forces against García II, marching across León and Galicia in a coordinated attack. While Sancho conquered the northern territories, Alfonso issued charters in the south, effectively carving up their younger brother’s kingdom.
• García fled to exile in Seville, leaving only Sancho and Alfonso to vie for ultimate control.

The Battle of Golpejera (1072) and Alfonso’s Exile

The final confrontation between the two brothers came in early January 1072, at the Battle of Golpejera, near the Carrión River (south of Santa María de Carrión, the seat of the powerful Beni-Gómez family).

• The battle began at dawn, with both sides fighting fiercely. By the end of the first day, Sancho’s Castilian forces were routed, and his army fled the field.
• However, Rodrigo Díaz de Vivar, later known as El Cid, rallied the demoralized Castilian troops, inspiring them to launch a renewed attack the following morning.
• In this second assault, Sancho II decisively defeats Alfonso VI, capturing him on the battlefield.

Following his defeat and capture, Alfonso VI is released into exile. He flees to his Moorish client Taifa of Toledo, where he seeks refuge under Muslim protection.

This victory leaves Sancho II as the most powerful of Ferdinand’s heirs, setting the stage for further conflict over the remaining territories of his divided father’s kingdom.