The daughter of Spain's King Ferdinand and Isabella, Catherine was just 16 when she married Henry's older brother Arthur in 1501. When Arthur died shortly thereafter, Catherine was left stranded. It wasn't until seven years later that she was able to marry Henry, who had become king. Henry believed that his union with Catherine would make Spain an ally in an imminent war with France. When war did break out, Catherine, like her mother before her, proved to be an excellent military strategist -- a "warrior queen." But as queen, Catherine's foremost job was to produce a male heir, and after many pregnancies, stillborns and children who died in infancy, only a daughter, Mary, survived. Henry was desperate for a son -- and after 20 years of marriage, he had fallen in love with a younger woman in his court. He sought an annulment, but as a Catholic, was unable to obtain permission from Rome. The younger woman, Anne Boleyn, convinced Henry that if he broke from the Catholic church, he would be able to declare the annulment himself -- and make her his new Queen.