Royal Leadership as a Balancing Act

John II left his heirs, Henry IV and the Catholic Monarchs, Isabella and Ferdinand, a bitter, dangerous, and widely followed quarrel between the city of Toledo and the heads of the House of Sotomayor, now counts of Belalcázar. Although John also bequeathed royal institutions and laws to resolve such conflicts, Crown officials lacked the capacity to do so. The history of the Belalcázar case, as the litigation was increasingly known, reveals that John had further bequeathed an influential group of magnates who were capable of pressuring rulers to observe more personal relationships with their great vassals, which could be used to block the continuation of the trial to a final verdict.

The Catholic Monarchs understood the special importance of royal justice in Castile. Both were members of the Castilian House of Trastámara, which had been established as the ruling dynasty when Henry II overthrew and murdered Peter I in 1369. Henry justified this act on the basis of king Peter's alleged failure to maintain justice in the kingdom. In 1465, Isabella's older half brother Henry IV had been symbolically removed from the throne and replaced by her younger brother Alfonso on exactly the same grounds. Although Ferdinand would become the male head of the House of Trastámara when his father, John II of Aragón, died in 1479, Isabella insisted in the marriage agreement of 1469 and afterwards that Ferdinand was no more than her co-administrator of justice in Castile and was equally bound “to guard justice and all the good usages, laws and customs of these kingdoms and domains.”