On 24 April 1558, 15-year-old Mary, Queen of Scots married 14-year-old Francis, Dauphin of France. Potentially this would unite the two countries. Catholics viewed Elizabeth I as the illegitimate child of Henry VIII, and so to them, Mary was not just Queen of Scotland and France, but of England as well. This placed her in conflict with Elizabeth and English Protestants.
Look in more detail at the Auld Alliance, how it came about and the lasting influence it has had on Scottish language, law and architecture.