Henry II of Castile, also known as Henry of Trastámara, from the Latin “Tras Tamaris” (or beyond the Tambre River), King of Castile and León (1366–1367, 1369–1379) was the first king of the Trastámara Dynasty. In summary, it was a minor branch of the house of Burgundy (or an “Iberian extension” of it), with presence in the kingdoms of Castile, Aragon, Navarre, and Naples. Most notably, it began playing an essential role in the kingdom of Castile, but after the Compromise of Caspe, its power extended decisively to the kingdom of Aragon (1412). Henry II was the illegitimate son of Alfonso XI and his lover Leonor de Guzmán. He waged a civil war against his stepbrother, Peter I, legitimate heir to the throne, as the son of Alfonso XI and Maria of Portugal, Queen of Castile. Henry’s determination to be recognized as king led him to employ the arts in a campaign to discredit his stepbrother and tarnish his image, portraying himself as a defender of the faith with the right to rule. He built the Royal Chapel (1371) in the main church of Córdoba (today’s Mosque/Cathedral) for the burial of his father and grandfather, Ferdinand IV, in order to underscore his connection to the royal line, and refurbished the Puerta del Perdón (Gate of Forgiveness) in 1377, the main entrance to the church, for use as a dramatic stage for public events.
After the death of Alfonso XI during the siege of Gibraltar in 1350, a victim of the Black Plague that struck Europe in the second half of the 14th century, his son Peter I (by name, Peter the Just or Peter the Cruel) ascended to the throne of Castile and León. Thus began the struggle for power between Peter’s illegitimate half-brothers, fruit of Alfonso XI’s relationship with his lover Leonor de Guzmán (a great-great-granddaughter of Alfonso IX), who bore him 11 children. The Trastámara line originated in this illegitimate lineage, whose first-born son bore the title of Count of Trastámara, including Henry, who ultimately would be king 
. According to the chronicle, “she was beautiful, the loveliest woman in the kingdom” 
. Alfonso XI endeavored to furnish his illegitimate children with titles and possessions to secure their futures 
Born in Seville on January 13, 1333, Henry was described by the chronicler Pedro López de Ayala as follows: “His body was small, but well built; he was white and blond, with good brains, he was energetic, and frank, and virtuous, and a very good receiver and honorer of the people” 
(p. 507). Through his mother’s mediation, he married Juana Manuel, a daughter of the famous writer and nobleman Don Juan Manuel and his third wife, Blanca de la Cerda. When Peter I found out about this union, he moved to have his stepbrother apprehended, so Henry took refuge in Asturias. A year later, in 1351, Peter agreed to have Leonor de Guzmán executed, as she had orchestrated her son Henry’s marriage to Juana Manuel, which provided him with the great prestige of her lineage, and wealth, thereby bolstering Henry’s threat to Peter.
To understand Henry’s achievements, it is necessary to appreciate the calamitous economic situation that had arisen due to the demographic crisis wrought by the Black Death, compounded not only by the war of the Two Peters (Peter I of Castile and Peter IV of Aragon) but also a civil war between petristas (supporters of Peter I) and enriqueños (backers of Enrique; that is, Henry), which became one more episode in the Hundred Years War due to the involvement of France, whose support Henry secured; and England, which supported Peter, who had turned to the Prince of Wales for help. Henry II, Count of Trastámara, managed to rally the nobles against Peter I in 1366, thanks to support from France and the Crown of Aragon, in addition to a carefully crafted campaign to depict his stepbrother as a tyrant. It is necessary to emphasize that Henry II would indirectly play an essential role in European history since the support of Castile to France would be consummated in the battle of La Rochelle (1372), resulting in an extreme fiasco of the English navy against the Castilian, led by the admiral A. Bocanegra. This fact would mean the beginning of the end of the Hundred Years War and would mark the decline of the English interests in France.
If there is one truly revolutionary aspect of Henry II’s reign that must be highlighted, one with profound consequences related to the image that he projected of himself through the arts, it was how, despite being a bastard son, he still managed to take the throne thanks to the support of the nobility. He rewarded them with ample and generous mercedes, favors in the form of goods, income, and privileges (hence, his nickname ‘the King of Las Mercedes’) and to convince the kingdom of his reign’s legitimacy, despite having risen to power through bloodshed.