He was the founder of the lineage of Enriquez, and is the first Admiral of Castile of his family since 1405, and first lord of Medina de Rio Seco.

Alfonso Enriquez remained hidden while living his uncle Pedro I of Castile, who ordered to kill his father in 1358 in the Alcazar of Seville.

Although contemporary Castilian chroniclers wrapped the figure of his mother in mystery and later genealogists do not mention her, other authors, for example, the Portuguese Fernão Lopes wrote in connection with events that occurred in 1384, that the Admiral was the son of a Jewess.

[citation needed] The "Memorial of old things" attributed to the dean of Toledo, Diego de Castilla, said Fadrique had Alfonso from a Jewess from Guadalcanal called Paloma (pigeon, dove).

It is conjectured that it must have been at the behest of his wife that the title of Admiral of Castile passed to him upon the death of her brother Diego Hurtado de Mendoza in 1405, who held that post.

In addition to military action at sea, this post also involved trying to obtain civil and criminal jurisdiction over all ports of the kingdom of Granada, culminating after three years with the taking of Antequera.

[2] In 1421, John II of Castile granted him the lordship of Medina de Rio Seco "for the many good and loyal and outstanding and distinguished services done to King Don Juan my grandfather and to King Henry my father and my lord, and still does to me," instead he chose to settle and establish primogeniture in favor of his children.

The poet and biographer Fernán Pérez de Guzmán, a contemporary of Alfonso's, described him as medium-sized, chubby, red-haired, discrete and not a talker.

In 1387, Alfonso Enriquez, posing as a servant, asked Juana de Mendoza (widowed by the Battle of Aljubarrota, August 1385), if she would marry his Lord (himself).