Infanta Maria
I Due Tristani is an Italian romance that tells the story of Tristan the Younger, the son of the famous Tristan and Iseult (Isolde of Cornwall), and his love for Maria, the daughter of King Juan of Castile.
The story begins with Tristan the Younger traveling to Castile to participate in a tournament. There, he meets Maria and falls in love with her at first sight. However, their love is opposed by King Juan, who wants to arrange a marriage between Maria and the Duke of Calabria, a powerful nobleman who is an ally of Castile.
Despite the obstacles, Tristan and Maria continue to meet in secret and profess their love for each other. They eventually decide to elope and flee to Brittany, where they live together in happiness for a time.
However, their happiness is short-lived. The Duke of Calabria discovers their whereabouts and send an army to attack them. Tristan fights bravely but is eventually captured and brought before the Duke, who orders his execution. Maria is heartbroken by Tristan’s death and dies of grief soon after. In the end, their tragic love story is remembered as one of the great romances of all time.
The romance is based on the French romance, Tristan de Nanteuil, which in turn is based on the Tristan and Iseult legend.
Source
I Due Tristani | 1555