One of Rébuffat's most famous accomplishments is his ascent of the six great north faces of the Alps. He began planning for his first ascent, the Grandes Jorasses, in the summer of 1938 at the age of 17, shortly after the first ascent of the mountain's north face by Italian mountaineers Riccardo Cassin, Gino Esposito, and Ugo Tizzoni. In 1943, Rébuffat made his first attempt at the summit but was not successful due to poor weather conditions. He returned to the mountain in July of 1945 and successfully climbed the north face with the assistance of Édouard Frendo. In August of 1949, he attempted and successfully completed an ascent of the northeast face of Piz Badile, during which he acted as a mountain guide for an amateur mountaineer. By this time, Rébuffat was among a handful of elite mountaineers to have climbed these faces. This led to his selection as one of the principal members of the 1950 Annapurna expedition. Over the next several years, he guided mountaineers, both new and experienced, up the remaining great north faces, the Petit Dru, the Matterhorn, the Cima Grande di Lavaredo, and the Eiger.