In brief, this official account (upon which 1954 Italian Karakoram expedition to K2 article is based) was that (1) Camp IX had been placed 250 meters higher than agreed and on the far side of difficult rocks; (2) Mahdi eventually lost fingers and toes due to severe frostbite caused by the enforced bivouac; (3) after the overnight bivouac Mahdi set off down before Bonatti; (4) Compagnoni and Lacedelli started ascending with supplementary oxygen at about 08:30; (5) they were using Dräger bottles which guaranteed a supply for twelve hours; (6) the summit was reached slightly before 18:00 when there would have been a reserve of oxygen of at least two and a half hours.