Mont Blanc as seen from Valdigne in Aosta Valley, Italy

The Mont Blanc was the highest mountain of the Frankish Empire under Charlemagne and the highest mountain of the Holy Roman Empire until 1792.[a]

In 1760, Swiss naturalist Horace-Bénédict de Saussure began to go to Chamonix to observe Mont Blanc.[1] He tried to summit it with the Courmayeur mountain guide Jean-Laurent Jordaney, a native of Pré-Saint-Didier, who accompanied De Saussure since 1774 on the Miage Glacier and Mont Crammont.

The first recorded ascent of Mont Blanc (at the time neither within Italy nor France) was on 8 August 1786 by Jacques Balmat and the doctor Michel Paccard. This climb, initiated by Horace-Bénédict de Saussure, who rewarded the successful ascent, traditionally marks the start of modern mountaineering.[2] The first woman to reach the summit was Marie Paradis in 1808.

 Mont Blanc from the TMBOwnership of the summit

At the scale of the Mont Blanc massif, the border between Italy and France passes along most of the main Alpine watershed, from the Aiguille des Glaciers to Mont Dolent, where it reaches the border with Switzerland. However, its precise location near the summits of Mont Blanc and nearby Dôme du Goûter is disputed.[3][4][5] Italian officials claim the border follows the watershed, splitting both summits between Italy and France. In contrast, French officials claim the border avoids the two summits, placing them entirely with France. The size of these two (distinct) disputed areas is approximately 65 ha on Mont Blanc and 10 ha on Dôme du Goûter.[6]

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.[citation needed] 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.[7] 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.[citation needed] 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.[citation needed] 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.

After the Napoleonic Wars, the Congress of Vienna restored the King of Sardinia in Savoy, Nice, and Piedmont, his traditional territories, overruling the 1796 Treaty of Paris. Forty-five years later, after the Second Italian War of Independence, it was replaced by a new legal act. This act was signed in Turin on 24 March 1860 by Napoleon III and Victor Emmanuel II of Savoy, and deals with the annexation of Savoy (following the French neutrality for the plebiscites held in Tuscany, Modena, Parma and Romagna to join the Kingdom of Sardinia, against the Pope's will). A demarcation agreement, signed on 7 March 1861, defined the new border. With the formation of Italy, for the first time, Mont Blanc was located on the border of France and Italy, along the old border on the watershed between the department of Savoy and that of Piedmont, formerly belonging to the Savoyard state.[8]

The 1860 act and attached maps are still legally valid for both the French and Italian governments.[8] In the second half of the nineteenth century, on surveys carried out by a cartographer of the French army, Captain JJ Mieulet, a topographic map was published in France, which incorporated the summit into French territory, making the state border deviate from the watershed line, and giving rise to the differences with the maps published in Italy in the same period.[9][10]

Modern Swiss mapping, published by the Federal Office of Topography, plots a region of disputed territory (statut de territoire contesté) around the summits of both Mont Blanc and the Dôme du Goûter. One of its interpretations of the French-Italian border places both summits straddling a line running directly along the geographic ridgeline (watershed) between France and Italy, thus sharing their summits equally between both states. However, a second interpretation places both summits, as well as that of Mont Blanc de Courmayeur (although much less clearly in the latter case), solely within France.[6]

NATO maps take data from the Italian national mapping agency, the Istituto Geografico Militare, which is based upon past treaties in force.[11]

 1832 Map of the Kingdom of Sardinia showing an administrative border passing through the summit of Mont Blanc. This was the same map annexed to the 1860 treaty to determine the current border between France and Italy.  Captain Mieulet map of 1865 placing the international border south of the watershed[9]  A Sardinian Atlas map of 1869 showing the international border on the watershed[12] Vallot  The original Vallot refuge (now rebuilt) near Mont Blanc summit, at an altitude of 4,362 m

The first professional scientific investigations on the summit were conducted by the botanist–meteorologist Joseph Vallot at the end of the 19th century. He wanted to stay near the top of the summit to undertake detailed research, so he built his permanent cabin.

Janssen observatory

In 1890, Pierre Janssen, an astronomer and the director of the Meudon astrophysical observatory, considered the construction of an observatory at the summit of Mont Blanc. Gustave Eiffel agreed to take on the project, provided he could build on a rock foundation if found at a depth of less than 12 m (39 ft) below the ice. In 1891, the Swiss surveyor Imfeld dug two 23 m-long (75 ft) horizontal tunnels 12 m (39 ft) below the ice summit but found nothing solid. Consequently, the Eiffel project was abandoned.

Despite this, the observatory was built in 1893. During the cold wave of January 1893, a temperature of −43 °C (−45 °F) was recorded on Mont Blanc, being the lowest ever recorded there.

Levers attached to the ice supported the observatory. This worked to some extent until 1906, when the building started leaning heavily. The movement of the levers corrected the lean slightly, but three years later (two years after Janssen's death), a crevasse started opening under the observatory. It was abandoned. Eventually the building fell, and only the tower could be saved in extremis.[13]

Air crashes

The mountain was the scene of two fatal air crashes; Air India Flight 245 in 1950[14] and Air India Flight 101 in 1966. Both planes were approaching Geneva Airport and the pilots miscalculated their descent; 48 and 117 people, respectively, died.[15] The passengers on flight 101 included nuclear scientist Homi J. Bhabha, known as the "father" of India's nuclear programme.[16]

Tunnel  Entrance of the Mont Blanc Tunnel in Italy

In 1946, a drilling project was initiated to carve a tunnel through the mountain. The Mont Blanc tunnel would connect Chamonix, France, and Courmayeur, Italy, and become one of the major transalpine transport routes between the two countries. In 1965, the tunnel opened to vehicle traffic with a length of 11,611 m (7.215 mi).[17]

1999 disaster

In 1999, a transport truck caught fire in the tunnel beneath the mountain. In total, 39 people were killed when the fire raged out of control. The tunnel was renovated in the aftermath to increase driver safety. Renovations include computerised detection equipment, extra security bays, a parallel escape shaft, and a fire station in the middle of the tunnel. The escape shafts also have clean air flowing through them via vents. Any people in the security bays now have live video contact to communicate with the control centre. A remote site for cargo safety inspection was created on each side: Aosta in Italy and Passy-Le Fayet in France. Here all trucks are inspected before entering the tunnel. These remote sites are also used as staging areas to control commercial traffic during peak hours. The renovated tunnel reopened three years after the disaster.[18]

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