Spain and England had a history of poor diplomatic relations, and it was common in the Fifteenth Century for members of a royal family to marry off a daughter or son to a child from another royal family, to establish an alliance between those two countries. Catherine of Aragon was the youngest child of King Ferdinand of Aragon and Queen Isabella of Castille, who almost immediately began looking for a political match for her. When she was three years old, she was engaged to Arthur, the son of Henry VII of England. Arthur was not even quite two at the time.
When Catherine was almost sixteen,…