Following a decisive victory at Agincourt in 1415, the English gained the upper hand in the conflict, occupying much of northern France. Under the Treaty of Troyes of 1420, England's Henry V became regent of France. By this treaty, Henry married Catherine, the daughter of the current French king, Charles VI, and would then succeed to the French throne upon Charles's death. The Dauphin of France (title given to the French heir apparent), Charles, the son of the French king, was then disinherited.