Engineers provided the brains (though not always the muscle) behind the construction of everything from field fortifications to roads and camps, and many spent their time in the familiar task of trench-digging, as Lieutenant John Glubb reported in early 1916.
During the battle last month the troops suffered heavily and were too tired to bury their dead. Many of them were merely trampled into the floor of the trench, where they were soon lost in mud and water. We have been digging out a lot of these trenches again, and are constantly coming upon corpses. They are pretty well decomposed, but a pickaxe brings up chips of bone and rags of clothing. The rest is putrid grey matter.
Source:
Holmes, Richard. "Steel and Fire." Tommy: The British Soldier on the Western Front, 1914-1918. London: HarperCollins, 2004. 451-52. Print.
Original Source Listed:
Glubb Into Battle p. 48.
Further Reading:
Lieutenant-General Sir John Bagot Glubb, KCB, CMG, DSO, OBE, MC / Glubb Pasha
In the 1860s, soldiers wrote their name on pieces of paper and pinned them to their clothes. In 1906 a round coin sized piece of aluminum was used, and in 1913 it was mandatory for all troops. The circular tags, handstamped with name, rank, serial number, unit, and religion were used during World War I.
src: http://taskandpurpose.com/a-brief-history-of-the-dog-tag/
But soldiers have carried various forms of identification for thousands of years. Ancient Romans had a piece of leather with their info and a authentication stamp - https://en.wikipedia.org/wiki/Signaculum