Since the French Revolution, the issue of the ownership of the summit has been debated. From 1416 to 1792, the entire mountain was within the Duchy of Savoy. In 1723, the Duke of Savoy, Victor Amadeus II, acquired the Kingdom of Sardinia. The resulting state of Sardinia was to become preeminent in the Italian unification. In September 1792, the French revolutionary Army of the Alps under Anne-Pierre de Montesquiou-Fézensac seized Savoy without much resistance and created a department of the Mont-Blanc. In a treaty of 15 May 1796, Victor Amadeus III of Sardinia was forced to cede Savoy and Nice to France. In article 4 of this treaty it says: "The border between the Sardinian kingdom and the departments of the French Republic will be established on a line determined by the most advanced points on the Piedmont side, of the summits, peaks of mountains and other locations subsequently mentioned, as well as the intermediary peaks, knowing: starting from the point where the borders of Faucigny, the Duchy of Aoust and the Valais, to the extremity of the glaciers or Monts-Maudits: first the peaks or plateaus of the Alps, to the rising edge of the Col-Mayor". This act further states that the border should be visible from the town of Chamonix and Courmayeur. However, neither is the peak of the Mont Blanc visible from Courmayeur nor is the peak of the Mont Blanc de Courmayeur visible from Chamonix because part of the mountains lower down obscure them.