James was the only son of Mary, Queen of Scots, and her second husband, Henry Stuart, Lord Darnley. Both Mary and Darnley were great-grandchildren of Henry VII of England through Margaret Tudor, the older sister of Henry VIII. Mary's rule over Scotland was insecure, and she and her husband, being Roman Catholics, faced a rebellion by Protestant noblemen. During Mary's and Darnley's difficult marriage, Darnley secretly allied himself with the rebels and conspired in the murder of the Queen's private secretary, David Rizzio, just three months before James's birth.