In 1863, he climbed the Grandes Rousses with William Mathews, Thomas George Bonney and his brother Jean-Baptiste Croz, and in 1864 he made the first traverse of the brèche de la Meije and the first traverse of the col de la Pilatte (with Edward Whymper, Horace Walker, A. W. Moore and Saas-Fee guide Christian Almer).

Of the latter expedition, Whymper was later to write, I cannot close this chapter without paying tribute to the ability with which Croz led us, through a dense mist, down the remainder of the Glacier de la Pilatte.

Never able to see 50 feet ahead, he still went on with utmost certainty, and without having to retrace a single step; and displayed from first to last consummate knowledge of the materials with which he was dealing.

[4] Croz then had to fulfil an engagement with Charles Hudson, during which – together with T. S. Kennedy – they made the first ascent of the Moine ridge of the Aiguille Verte, whilst Whymper attempted to join forces with the Valtournenche guide Jean-Antoine Carrel.

According to Claire Engel, At each step [on the descent] Croz had to make Hadow's feet secure, and to do so he had to lay down his ice axe so that he had no support himself.

'[6] Whymper subsequently 'had to see to the fund for Croz's widow and he took on, later on, much care over a suitable memorial for the man who had been, despite occasional differences, undoubtedly his favourite guide.