Although Tullis and Diemberger finally made the summit on 4 August 1986, making Tullis the first British woman to do so, they were exhausted from spending several days above 8,000 metres; 26,000' (known as the death zone). On the descent, Tullis slipped and fell; although Diemberger's belay successfully saved them both, it is likely that Tullis suffered internal or head injuries that began to affect her vision and co-ordination.
