Aiguille du Dru: Petit Dru, Grand Dru and historic routes

The Grand Dru stands at 3,754 m and the Petit Dru at 3,733 m according to English Wikipedia and the summit waypoint on camptocamp, or 3,730 m according to French Wikipedia. The sources therefore differ by three metres on the Petit Dru. Wikidata places the summit at 45.93° north and 6.96° east, in Haute-Savoie. The two peaks are not an independent summit. They rise on the west ridge that descends from the Aiguille Verte and continue along the Flammes de Pierre ridge. To the south, they overlook the Charpoua valley and glacier; to the north, the Drus glacier.

The British climbers Clinton Thomas Dent and James Walker Hartley, with the guides Alexander Burgener and Kaspar Maurer, on 12 September 1878. English Wikipedia specifies that they followed the south-east face.

Jean Charlet-Straton, Prosper Payot and Frédéric Folliguet reached the Petit Dru on 29 August 1879, eleven and a half months after the Grand Dru. English Wikipedia states that they went by the south face and the south-west ridge. That 1879 line has remained the normal route to the summit.

Two dates circulate, and this page gives both readings. French Wikipedia places the first traverse from the Grand Dru to the Petit Dru on 31 August 1887, by François Simond, Émile Rey and Henri Dunod. English Wikipedia credits the first traverse of both summits to E. Fontaine and J. Ravanel, on 23 August 1901. None of the sources consulted explains the discrepancy.

From 17 to 22 August 1955, the Italian Walter Bonatti climbed the south-west pillar of the Petit Dru alone, with five bivouacs on the wall. The pillar stood more than 500 m high and carried his name until it collapsed.

Pierre Allain and Raymond Leininger opened the north face on 1 August 1935. The west face fell in 1952, in two pushes by A. Dagory, Guido Magnone, Lucien Bérardini and Marcel Lainé, on 5 July and then from 17 to 19 July. Gary Hemming and Royal Robbins traced the Directe américaine from 24 to 26 July 1962, and Robbins returned with John Harlin for the Directissime américaine from 10 to 13 August 1965. English Wikipedia counts this Directissime among the routes destroyed by the rockfalls, along with the Bonatti Pillar.

The west face lost 335,000 m³ of granite between 1905 and 2005, give or take 15,000 m³, according to the survey by Ludovic Ravanel and Philip Deline published in the journal Géomorphologie. The collapse of 29 and 30 June 2005 wiped out the whole Bonatti Pillar and deposited debris over 90,000 to 95,000 m² of the Drus glacier. The two geographers identify permafrost degradation as the main triggering factor of the collapses they document. The wall reaches 1,000 m in height, and the detachment scars range from about 3,130 to 3,660 m.

The south-west ridge is graded D- with commitment grade IV and equipment grade P3 on camptocamp, and includes free-climbing passages up to 5c. The collaborative database counts 960 m of elevation gain from the Charpoua hut, including 800 m of difficulties, after the glacier crossing that begins at the hut. The route passes a gendarme at 3,361 m, a triangular névé, a wedged-block passage and a red roof, before the ice gully leading to the summit.

The Charpoua hut stands at 2,841 m, at the foot of the south side of the Drus, and has 12 beds. It is reached from the Montenvers station, at 1,913 m, by crossing the Mer de Glace and then taking the Mer de Glace balcony path, whose access was changed in 2016. It serves as a base for climbs on the Drus and the Aiguille Verte. The original building, built between December 1903 and July 1904 by the Club des sports alpins de Chamonix, had only one room. It closed on 25 August 2022 to be rebuilt. The Compagnie des Guides de Chamonix, the owner, lists it again in its summer calendar, from June to late September.