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, in 1501, she made the journey to England. When she and Arthur were married on November 14, 1501, in old St. Paul's Cathedral, London. Catherine was escorted by Arthur's younger brother, Henry. Following the ceremony, the young couple moved to Ludlow Castle on the Welsh border.
Less than six months later Arthur died, possibly of the "sweating sickness". Historians speculate that the history of England would have changed drastically if Arthur had lived a year longer.
Catherine was now a widow and still young enough to marry again, so on June 25, 1503, she was formally engaged to the king's second son, Henry, now Prince of Wales. The marriage, however, didn't take place during Henry VII's lifetime. Henry made use of the presence of the unmarried princess in England to extort new conditions, and especially to secure the marriage of his daughter Marry to the archduke Charles V. By 1505, when Henry was old enough to wed, Henry VII wasn't as keen on a Spanish alliance, and young Henry was forced to reject the engagement.
Catherine's future was uncertain for the next four years. When Henry VII died in 1509, on one of...