In 1574, following the death of his brother Charles IX of France and the accession of his other brother Henry III of France, he became heir to the throne. In 1576 he was made Duke of Anjou in succession to his brother Henry.
In 1576 he negotiated the Peace of Beaulieu during the French Wars of Religion. In 1579 he was invited to become hereditary sovereign to the United Provinces. In 1581 arrangements began to be made for his marriage to Elizabeth I of England.