Following eight failed attempts on the Matterhorn starting from 1861, Whymper was recalled to London in the summer of 1864 and offered the services of Croz to his friend Adams-Reilly, advising him to make an attempt on the mountain (all three had been in a party that had made the first ascent of Mont Dolent that year).
This never came to anything, and the next year Croz was again employed by Whymper.
Together with Christian Almer and Franz Biner they made the first ascent of the Grand Cornier, and the first ascent of Pointe Whymper on the Grandes Jorasses.

On the Matterhorn, Croz and Whymper tried a route via a couloir on the south-east face but were unsuccessful.
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.
When this proved impossible (Carrel instead leading an Italian party on an attempt on the Italian ridge of the mountain), Whymper teamed up with Lord Francis Douglas and the two Zermatt guides, Peter Taugwalder father and son.
Eventually this party decided to share the attempt on their common objective of the Hörnli ridge with Croz and Hudson, who had been joined by Hudson's protégé – the young, inexperienced and badly shod Douglas Hadow.

After this party of seven successfully made the first ascent of the Matterhorn on 14 July 1865, the order on the rope during the descent was Croz going down first, followed by Hadow, then Hudson, Douglas, old Peter Taugwalder and Whymper, with young Peter Taugwalder bringing up the rear.
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.
Suddenly, while Croz was turning round to continue the descent, after having made Hadow secure, Hadow slipped and both of his feet struck Croz in the back.
The guide lost his footing and fell headlong down the steep slope, dragging the boy with him.
Hudson came next, then Douglas; none had time to react.

The rope (an old, thin and worn line) between Douglas and old Peter Taugwalder snapped, saving the remaining three members of the party – Taugwalder father and son, and Whymper.
Croz's body, together with those of Hudson and Hadow (but not Douglas), were recovered from the Matterhorn glacier.
Croz was buried in the south side of Zermatt churchyard, on the other side from the graves of Hudson and Hadow.
Whymper wrote: 'The inscription that is placed upon his tomb truthfully records that he was beloved by his comrades and esteemed by travellers.'
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.'
Following eight failed attempts on the Matterhorn starting from 1861, Whymper was recalled to London in the summer of 1864 and offered the services of Croz to his friend Adams-Reilly, advising him to make an attempt on the mountain (all three had been in a party that had made the first ascent of Mont Dolent that year). This never came to anything, and the next year Croz was again employed by Whymper. Together with Christian Almer and Franz Biner they made the first ascent of the Grand Cornier, and the first ascent of Pointe Whymper on the Grandes Jorasses.
On the Matterhorn, Croz and Whymper tried a route via a couloir on the south-east face but were unsuccessful. 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. When this proved impossible (Carrel instead leading an Italian party on an attempt on the Italian ridge of the mountain), Whymper teamed up with Lord Francis Douglas and the two Zermatt guides, Peter Taugwalder father and son. Eventually this party decided to share the attempt on their common objective of the Hörnli ridge with Croz and Hudson, who had been joined by Hudson's protégé – the young, inexperienced and badly shod Douglas Hadow.
After this party of seven successfully made the first ascent of the Matterhorn on 14 July 1865, the order on the rope during the descent was Croz going down first, followed by Hadow, then Hudson, Douglas, old Peter Taugwalder and Whymper, with young Peter Taugwalder bringing up the rear. 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. Suddenly, while Croz was turning round to continue the descent, after having made Hadow secure, Hadow slipped and both of his feet struck Croz in the back. The guide lost his footing and fell headlong down the steep slope, dragging the boy with him. Hudson came next, then Douglas; none had time to react.
The rope (an old, thin and worn line) between Douglas and old Peter Taugwalder snapped, saving the remaining three members of the party – Taugwalder father and son, and Whymper. Croz's body, together with those of Hudson and Hadow (but not Douglas), were recovered from the Matterhorn glacier. Croz was buried in the south side of Zermatt churchyard, on the other side from the graves of Hudson and Hadow. Whymper wrote: 'The inscription that is placed upon his tomb truthfully records that he was beloved by his comrades and esteemed by travellers.' 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.'
Michel Croz