ABSTRACT
As the only descendant of King Pedro I of Castile (1350-69), who was murdered by his half-brother Enrique Trastamara in 1369, Catalina had her own rights to the crown of Castile. She had been brought up as the heir to the throne by her father, John of Gaunt, the duke of Lancaster, who had envisaged a crown for himself and his wife, Constanza of Castile. However, John's 1386 campaign on Castilian soil failed, leaving him with marriage policies as the only way to make a profit out of his enterprise. Catalina's marriage to the Trastamaran heir Enrique III solved the succession problem in Castile and gave Catalina a number of privileges, which she played earnestly in favor of the crown-first, as princess of Asturias, and later, as queen.1
