Carlos I was king of Spain and Germany from 1500 to 1558. He succeeded to the thrones of Castilla, Aragón, and other territories in Europe and the Americas. Carlos married Juana, who was known as "Juana the Mad," and they had a son named Felipe II. Carlos fought in multiple wars against the French king Francisco I to defend his territories in Europe and restore Christianity globally, but was unsuccessful in stopping the expansion of Lutheranism. He decided to leave his vast empire to his son Felipe II due to his failures.