Mary was the oldest daughter of James II, King of England. When she was fifteen she married Willem III, who was 27 at the time. Mary and Willem were cousins, as Willem’s mother – Mary, Princess Royal – was Mary’s father’s sister. Though Willem (William) and Mary had very different personalities, they eventually grew close and theirs was a happy marriage.
In 1688, their lives changed dramatically: Willem was asked to invade England and dethrone Mary's father. After the successful invasion William and Mary were crowned King and Queen of England, Scotland and Ireland. From that point on Mary lived in England to take care of affairs of state there. She never saw the Netherlands again.
Mary died of smallpox at the age of 32. Willem never remarried. After his death Mary’s younger sister Anne became Queen of England, Scotland and Ireland.