In reply to Mr-Cowdrey:
No idea on the identity of the British officers, but I'll guess they were SOE types, but the commander of the German attack was one Hauptmann Karl Siegle, killed in the ambush you describe his body was never recovered and his grave is recorded as the Vallee Blanche Glacier. I hope he rests in peace.
The Battle was apparently recreated just after the war for a film by Marcel Ichac, I've done a very brief search but can't immediately see it anywhere.
The shelling would probably have been absorbed by the Snow, if you say that 2m fell during the battle then it's very likely that shells falling in snow buried themselves and exploded several metres down. The artillery used would have been light mountain guns, not heavy calibre stuff. The German mountain gun was 75mm and the French one may well have been the 65mm. These shells were not much bigger than a 500ml beer can and they won't have left much impression on Chamonix granite. The article in ATB has a good picture of one of the German guns above Entreves, and I should mention it is not dedicated solely to this action but to the many skirmishes that took place at that time in the alps. Glacier shrinkage might well reveal many secrets in the coming years, not least a lot of scrap iron.
Another interesting Vignette is that one of the French officers was Lt. Col. Alain le Ray who was the first man to successfully escape from Colditz in 1941.
Post edited at 14:18