King Charles II was the son of Charles I of England, Scotland and Ireland, and his wife Queen Henrietta Maria, the sister of King Louis XIII of France. He was named Prince of Wales at about age 8. Charles participated in the battles of the English Civil War even as a young teenager. In 1646, when the Royalists were losing the war, he fled into exile in France, where his mother was already living. Later he moved to The Hague for support from his sister Princess Mary and her husband William II, Prince of Orange. Charles declared himself King after his father was executed by the Puritans in 1649. After many further years of fighting, defeats, and exile, Charles II was remarkably recalled to the throne when the death of the Puritan leader Oliver Cromwell caused a political crisis in Britain. On May 29, 1660, his 30th birthday, he entered London to great public acclaim. He was called the Merry Monarch in reference to the liveliness and hedonism of his Restoration court, and his numerous mistresses and illegitimate children. King Charles was especially fond of his younger sister Henrietta-Anne, known in the family as "Minette," who married her cousin Louis, Duke of Orleans; many of their letters survive.