Juana entered almost ten years later. In 1552 the princess, 17 at the time, married the heir to the Portuguese throne. When he died two years later, she returned to Spain. Young, beautiful, and aware of her royal position and power, Juana was also endowed with a talent for ruling. While her brother, Philip II of Spain, was in England as husband of Mary Tudor, he made Juana regent. From 1554 to 1559 she was the effective ruler of Spain. Juana had an additional ambition: to become a Jesuit. Telling none of her family, she informed Spanish grandee Francis Borgia, an early Jesuit, that she wanted to join the Society of Jesus. The idea was heaped with danger for the Society. Her father, Emperor Charles V, and her brother Philip would be furious with her and the Jesuits for wrecking possible future dynastic marriage plans for Juana. Yet, the new, small, and in some places highly suspect Society could not afford to alienate Juana—depending in part on her good favor for its existence in Spain. The Society in 1554 had officially been in existence for only fourteen years, yet by Ignatius’s death in 1556, there were already 1,000 Jesuits. Men were flocking into the order enthusiastically. Women, too, were attracted and wanted either to found a separate female branch of the Society under the control of the general or to enter directly into the Society itself.

Source: Secret, Perilous Project: A Woman Jesuit