In 1506, when Philip of Burgundy and Juana of Castile visited England after their ship had been blown off course, they took refuge with Henry VII. While they were there, Henry’s daughter Mary played a key role in entertaining them. They were so impressed with the young princess that negotiations began for a marriage alliance between Mary, and Philip’s son, Charles who was five years younger than her.
Philip died later that year. However, Maximilian - the Holy Roman Emperor and Charles’s grandfather - continued these negotiations, keen for the marriage to go ahead. Once Henry VII died, Henry VIII was still content for this to be pursued, despite being distracted by war, and wanted the matter settled by 1514, when Charles would turn 13.
Despite apparent interest from both parties, by the summer of 1514, Maximilian had decided that he would prefer to pursue peace with France and therefore wanted to land his grandson’s marital alliances elsewhere. Mary was forced to formally repudiate this betrothal, much to the distress of both Henry VIII and Katherine.
Henry (or more likely Wolsey) moved quickly, and within a week Mary was betrothed to Louis XII, the King of France. It's often fictitiously written that Mary agreed to this under the condition she would be allowed to choose her next husband. However tempting a narrative this may be,there’s no evidence that she was anything more than an obedient sister to the King.
In October 1514 she left for France and experienced a terrible crossing which led to at least one ship being shipwrecked. This left her so unwell that she had to be carried ashore. After a day of rest, Mary met with her new husband and their marriage was celebrated. The only bump in the road was Louis's displeasure at the 100 people she brought with her and he consequently sent them away. After some negotiation it was agreed that she could have a small group of English ladies, one of whom was Anne Boleyn.
In November of 1514 Mary was crowned Queen of France, but by early January, Louis XII had died. Within just over a month of being crowned she became a widow.
Henry sent his close friend Charles Brandon to escort Mary home to England. However, Brandon and Mary secretly married- much to the anger of Henry given that marrying within the court without the King’s permission was ill advised, even more so when the bride in question is a sibling of the monarch!
After promising Henry a significant amount of money, he calmed down and forgave the new couple. Funny that.