On the 1954 Italian expedition to K2 (led by Ardito Desio), Achille Compagnoni and Lino Lacedelli became the first people to reach the summit of K2, 8,611 metres (28,251 ft), the second-highest mountain in the world. They reached the summit on 31 July 1954. K2 is more difficult to climb than Mount Everest, 8,849 metres (29,032 ft), which had first been climbed by a British expedition in 1953.
Three earlier unsuccessful American attempts on the mountain had identified a good route to use. Desio felt Italy's earlier exploration of the Karakoram region gave good reason to mount a major expedition which he did on a grand scale, following the American route up the south-east ridge. Progress towards the summit was repeatedly interrupted by storms, and one member of the team died rather unexpectedly. Desio considered abandoning the expedition so as to try again by returning later in the year, but weather conditions improved allowing them to edge closer to the top of the mountain. At last, the two lead climbers reached the summit as the sun was about to set and they had to descend in the dark. They and two colleagues went on to suffer from severe frostbite.
The fact that the summit had been reached was never doubted – Compagnoni and Lacedelli had been seen by their colleagues near the summit and they had taken photographs and even a movie film from the top – but all the same the expedition became mired in argument. After a prolonged controversy, the official 1954 account of the expedition eventually became discredited, and a second official account was published in 2007 which largely confirmed the claims another member of the expedition, Walter Bonatti, had been making for over fifty years.