This three-quarters portrait is especially direct, thanks to the absence of any background elements other than the model´s powerful shadow. It presents don Sebastian in the final years of his brief life, dressed in the Spanish style, with a black jerkin and matching cape that bring out the sumptuousness of his breeches and doublet, embroidered in gold on a white background. To convey his condition as a Christian soldier, the king holds the pommel of his sword and wears the cross of the Order of Christ—as king of Portugal, he was grand master of that order—on his chest. The gloves in his right hand are a common sign of distinction in portraits of the Habsburgs, especially in those of his mother, the infanta doña Juana.

Sebastian was born in Lisbon in January 1554, just days after the death of his father, Prince John, who was King John III´s only son. His mother, Spanish infanta Juana de Austria, returned to Castile four months after his birth, so he was raised by his paternal grandmother, Reagent Queen Catherine. Reasons of state kept Juana from ever seeing her son again, so the portraits that arrived frequently in Spain were her only way of following her son´s growth. A youth educated in knightly values and eager to become the armed wing of the Catholic cause, he ignored wiser council and traveled to Africa in June 1578, where he perished in battle on the plains of Alcazarquivir on August 5 of that same year. His body was never found, and he thus became a legendary figure. As he had no direct heirs, Portugal became a part of the Spanish crown through dynastic inheritance. This generated a phenomenon known as "sebastianism," which lasted for years, and consisted of individuals who attempted to pass for the monarch, claiming they had finally been freed from their imprisonment.

Esplendores de Espanha de el Greco a Velazquez, Río De Janeiro, Arte Viva, 2000, p.55