'I have often wondered," the alpinist Walter Bonatti wrote in his memoir The Mountains of My Life, "whether I was born a loner or became one." Bonatti, who has died aged 81 from cancer, not only did several of his greatest climbs alone, but chose to do so as a pointed response to what he regarded as the dishonesty of those who had misrepresented him.
Despite his elegant new climbs on the Grand Capucin and the Petit Dru in the French Alps, and the first ascent of Gasherbrum IV in the Karakoram, Pakistan, it was more often his controversial role in the first ascent of K2 in 1954, and the terrible storm on Mont Blanc in 1961 that killed four of his companions, that attracted attention. He was thin-skinned, but essentially honourable, and by the end of his life all shadows over his reputation had been dispelled, leaving him widely seen as among the greatest mountaineers ever.
An only child, born in Bergamo, in Lombardy, Italy, Bonatti spent his childhood in the Po valley dreaming of adventure. The second world war left his family impoverished, and as an adolescent living in Monza, he escaped by walking in the Grigna, the limestone massif above the town of Lecco, where he acquired his taste for climbing.
Thanks to his natural ability and fierce ambition, he quickly became one of the foremost alpinists in Italy, the leader of a group that included Andrea Oggioni, Emilio Villa and Mario Bianchi. With these three, and barely 19 years old, Bonatti made the fourth ascent of the Walker spur on the Grandes Jorasses, the masterpiece of Italy's pre-war genius, Riccardo Cassin.
Bonatti was not content to follow the climbs of a previous generation. In July 1951 he did his first significant new climb with the Turin climber Luciano Ghigo, the east face of the Grand Capucin, a skyscraper of granite in the shadow of Mont Blanc. His home town of Monza laid on a reception for the young hero, though the celebrations were sullied by the sudden death of his mother.
During his 15-month military service in the Alpini, when he instructed mountain troops, he met Carlo Mauri, one of his most important partners and best friends. On demobilisation, they climbed the north face of the Cima Ovest di Lavaredo, in the Italian Alps, in winter for the first time, in February 1953.
By now Bonatti was a star, and it was impossible for the Italian Alpine Club to omit him in the team gathered to attempt K2, at 8,611m (28,251ft) the world's second-highest mountain. At the climax of the expedition, Bonatti and a Pakistani porter called Amir Mahdi brought crucial oxygen supplies up to the top camp, where Lino Lacedelli and Achille Compagnoni were poised to make their summit bid.
Yet the tent was not where they had expected to find it and as dusk fell, Bonatti realised in horror that the pair were still some distance above him. They shouted down for him to dump the oxygen and descend; there was no room for Bonatti and Mahdi to take shelter with them in the tent. But it was too late to descend, and the two men faced a freezing bivouac at 8,100m. Mahdi suffered severe frostbite.
Lacedelli and Compagnoni, using the oxygen brought up to them, reached the summit and Italy celebrated. Yet Bonatti found his contribution overlooked in official accounts, and was ostracised by the rest of the team for reasons he could not understand. To prove himself, he returned several times to a beautiful pillar of rock on the Aiguille du Petit Dru above the Arve Valley in the French Alps. Finally, and climbing alone, he spent five days piecing together one of the greatest rock climbs in the world.
"It was like living in another world," he wrote. "Like entering another dimensions, like being in a mystical, visionary state in which the impossible did not exist and anything could happen." He dreamed of returning to K2 and climbing in alpine style without oxygen, but no one took him seriously. It would be decades before his vision was realised.
He was, however, selected to join Cassin's team to take on the elegant and difficult unclimbed peak Gasherbrum IV in the Karakoram. Although just below 8,000m, their route, the north-east ridge, was not repeated until 1999.
There were other expeditions, to Peru and Patagonia, but in 1961 a tragedy occurred that led to further press hostility in Italy. Attempting a granite pillar on Mont Blanc's remotest face, a team of seven Italian and French climbers, including Bonatti, was caught in a vicious storm that lasted days. Four of them died but Bonatti's desperate efforts helped save the life of Pierre Mazeaud, later a French politician. Bonatti was awarded the Légion d'honneur in France but at home faced unjustified criticism for his actions.
Soon afterwards, he published his first memoirs, Le Mie Montagne (published in English as On the Heights), which included a different take on what had happened on K2. The Italian Alpine Club was not impressed, and the leader of the expedition, Ardito Desio, became Bonatti's enemy. As Italy celebrated the 10th anniversary in 1964, a newspaper article accused him of attempting to steal Lacedelli and Compagnoni's oxygen and deserting Mahdi. Bonatti sued for libel and won, but his reputation remained tarnished.
In the winter of 1965, he climbed a new route on the north face of the Matterhorn, partly to celebrate Edward Whymper's first ascent in 1865. At a reception in Courmayeur to celebrate this adventure, Bonatti returned to his car to find all four tyres slashed.
Depressed at the hostility he faced, Bonatti quit alpinism to become a journalist, working for Epoca magazine in the remotest corners of the Earth, producing the kinds of story that had inspired him as a boy. His later memoirs, Montagne Di Una Vita (1994, translated as The Mountains of My Life), is a classic of mountaineering literature. In 2008, following Lacedelli's admission that Bonatti had told the truth, the Italian Alpine Club confirmed his version of events.
Bonatti is survived by his partner, Rossana Podestà. An earlier marriage ended in divorce.