On 8 May 1978, Messner and Habeler reached the summit of Mount Everest, becoming the first men known to climb it without the use of supplemental oxygen. Before this ascent, it was disputed whether this was possible at all. Messner and Habeler were members of an expedition led by Wolfgang Nairz along the southeast ridge to the summit. Also on this expedition was Reinhard Karl, the first German to reach the summit, albeit with the aid of supplemental oxygen.
