This picture was taken on November 18, 1916, last day of the Battle of the Somme.
It shows a group of Scottish Highlanders walking down a muddy road on the Ancre.
The first snow fell on the Somme on November 17. The next day was the final day of the battle, which had raged since July 1. It had been four-and-half months of battle and well over a million dead.
For a bit more about the Battle of the Somme, read Wounds, Scars, and Terriers at Battle of the Somme.