Sancho IV of Castile

Sancho IV of Castile
May 12, 1258 – April 25, 1295

Sancho IV of Castile was born on May 12, 1258, in Valladolid, Castile. The second son of King Alfonso X and Queen Violant of Aragon, Prince Sancho wasn’t intended to inherit the throne. Instead, the prince’s elder brother, Ferdinand, was his father’s heir. As he grew, Sancho became an ambitious yet ruthless man. It’s unknown when he began harboring a desire to claim the Castilian throne. However, his ambition became apparent after his elder brother’s death in 1275.

When Alfonso X traveled abroad in 1274, Ferdinand became his regent. During his regency, the Marinids launched an invasion of Castile. In turn, the prince raised an army to confront the invaders. During the Battle of Ecija, Ferdinand died fighting. Despite his early demise, the 19-year-old prince left behind two young sons: Alfonso and Ferdinand. Having secured the dynasty’s succession for another generation, Alfonso viewed his grandson Alfonso as his new heir.

Although the line of succession rightfully fell to Prince Alfonso, Sancho refused to accept being passed over. Despite his father’s wishes, the prince claimed to be Alfonso X’s actual heir. With the backing of the Castilian nobility, Sancho became more forceful in pressing his claim. After failing to resolve the issue peacefully, the prince engaged in a civil war against his father. After besting the king in 1282, Sancho officially became Alfonso’s heir. The embittered king never forgave his son and left behind a will disinheriting Sancho from the succession.

King of Castile

Alfonso X of Castile
Alfonso X of Castile

After Alfonso X’s death on April 4, 1284, the king’s will was ignored, and the prince became King Sancho IV of Castile. Despite his support, many still viewed Sancho as a usurper. A faction arose in favor of Prince Alfonso, threatening Sancho’s rule. The king’s younger brother, John, rebelled against Sancho on behalf of their nephew. After crushing the rebellion, Sancho imprisoned John while executing thousands of his followers.

Outside Castile, Alfonso’s faction had the support of Aragon. A capable politician, Sancho IV created an alliance with Aragon by marrying his eldest daughter to King James II in 1291. With Aragon neutralized, the king focused on fighting the Marinids. Having pardoned his brother, John repaid Sancho by allying with the enemy. Encouraging an invasion, the Marinids attacked the town of Tarifa.

The Castilians successfully defended the town until the royal army arrived. Sancho IV rallied his troops and managed to overcome the invaders, causing the Marinids and John to flee. Upon his victory, the king finally secured his throne. However, Sancho wouldn’t enjoy a peaceful reign for long. In 1295, the king’s health began to decline. As he lay dying, Sancho appointed his wife as his son’s regent. On April 25, the king succumbed to his illness and died at age 36.


Sancho IV of Castile proved to be a capable politician, yet his reign was troubled. Despite his capabilities, the king was widely viewed as a usurper, causing many internal and external problems. Although his position remained weak, Sancho overcame each challenge to his kingship. Sancho overcame opposition from his family, Aragon, and the Marinids. By the end of his life, the king had crushed his enemies and secured the throne for his descendants.


Encyclopædia Britannica, inc. (n.d.). Sancho IV. Encyclopædia Britannica. Retrieved February 5, 2022, from (n.d.). .” The Columbia Encyclopedia, 6th ed.. . 28 Mar. 2022 . Retrieved February 7, 2022, from


Andy Tree

I'm a European history enthusiast who seeks to share his passion with others. I hope to inform and inspire readers with my posts!

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