Two days before her husband's death in 1650, Mary gave birth to a son, William III of Orange, who later became king of England, Scotland and Ireland. Mary, who became the only guardian of her son, was not popular in the Netherlands because of her support of her brothers and her difficult relationship with her mother-in-law Amalia of Solms-Braunfels, who considered the princess young and inexperienced. After the restoration of the monarchy in England in 1660, Mary departed for celebrations in London, where she fell ill with smallpox and died.