In 1959, aged 55, Briggsy took command of an expedition up 26,867-foot Mount Cho Oyu after its leader, Mme. Claude Kogan of France, another climber, Mlle. Claudine van der Straten-Ponthoz, and two Sherpa porters had perished in an avalanche at 23,000 feet. Their attempt to scale the sixth highest mountain in the world was the first time in history that an expedition composed entirely of women (excepting guides and porters) had ever challenged such a peak.