After his father’s death in 1454, he was proclaimed king. Enrique earned the nickname “the Impotent” primarily because he failed to produce an heir, though his faltering leadership only reinforced the title. He married Blanca II of Navarre in 1440, at the age of fifteen. On their wedding night, they failed to produce the expected bloodstain on the bedsheet. The marriage was annulled after thirteen years.

It was later determined that he suffered from eunuchoid dysplasia, which resulted in complete impotence within the marriage. However, it was claimed that this condition did not affect his relations with other women. Yet testimonies from individuals such as Guiomar de Castro confirmed that penetration was consistently absent in his relationships. Guiomar, a lady-in-waiting of exceptional beauty, was rumored to have had a romantic involvement with Enrique.

To remedy this deficiency, the king underwent medical treatments — at least once by a renowned Jewish physician named Samaya. The historical record, pieced together from surviving testimonies, concludes that Enrique’s impotence, though certain and well-documented, could not have been absolute. As a result, historians lack sufficient evidence to determine whether any children attributed to him were biologically his.