Born in 1930, he was at the end of the 1950s and throughout the following decade one of the greatest exponents of world mountaineering, according to some observers inferior only to Walter Bonatti. His mountaineering is the child of the technical evolution after the Second World War, when pitons, even expansion bolts, and new materials such as down jackets and nylon ropes made their overbearing appearance.
The "artificial" ascents were born, which the French guide and writer Roger Frison-Roche defines as: "deformation of the way of going up the mountain, provoked by the fact that all the important peaks have been climbed". The strategy thus becomes that of the Himalayan siege, i.e. real expeditions overloaded with various tools and artifices. In this vein, Desmaison can boast the opening of the Jean Couzy or 'French' route on the Cima Ovest di Lavaredo (with P. Mazenaud), which cost the use of 350 pitons, of which about thirty were expansion bolts.
In the 1960s, however, the challenges changed, although he was still among the participants in the pharaonic expedition of the flower of transalpine mountaineering launched to the conquest of Jannu (7710m), today called Kumbhakarna, in the Kangchenjunga massif, an extremely technical climb as well as being made difficult by the environmental conditions.
The new frontiers became solitary and winter climbs, although in themselves they did not constitute conceptual novelties. Having set out to challenge the cold and the ice, Desmaison collected a series of exceptional first ascents: starting in 1960, the North-West Face of Mount Olan, the West Face of Petit Dru, the Central Pylon of Frêney with Robert Flematty (an ascent that would become symbolic for its length, altitude and isolation), and finally in 1968 the Linceul Glacier on the Grandes Jorasses, tackled before the current evolution of ice material.
In 1966, the first 'stunt' of his career: Desmaison, Mick Burke, Gary Hamming and others rescued two German mountaineers stranded on the west face of the Petit Dru. The rescuers face great difficulties magnified by the bad weather, but they achieve their goal, in fact humiliating the official rescuers, who had deployed a less effective strategy. A sin of insubordination that cost Desmaison his expulsion from the Compagnie des Guides in Chamonix, with a whole tail of controversy and public exchanges of accusations.
In February 1971, a second key episode in his career: he set off to open a new route on the Walker Spur of the Grandes Jorasses together with the young Serge Gousseault, and encountered great difficulties that delayed and complicated the ascent until his climbing partner was completely exhausted and died after 11 days on the wall. A series of misunderstandings and spats slow down the rescue machine abnormally. Desmaison does not dare abandon his companion and is rescued when he is at the end of his strength: he will survive by a miracle. Needless to point out the storm of controversy that followed.
The following year, however, Desmaison had already regained all his strength and proved it by soloing the entire Peuterey ridge, the longest route in the Alps. Finally, in January 1973, he honoured the memory of his deceased companion by completing the feat missed by only eighty metres, this time in the company of Michel Claret and Giorgio Bertone.
René Desmaison's last battle came to an end on 28 September 2007 at the Timone hospital in Marseilles, where the great mountaineer passed away due to a serious illness that had been affecting him for some time. His ashes, according to his wish, were scattered on the Devoluy massif in the Hautes-Alpes department, where the famous mountaineer lived in his last years.