By the end of the Great War, it is estimated that over a million horses, mules and donkeys were in the service of the British and Empire expeditionary forces on all fronts, nearly half a million of them in France. (1) Many of them died — different sources give different figures, none less than a quarter of a million (1,2).
Horses were vulnerable to disease as well as to injury from their work in difficult territory and, of course, from shelling.There were no trenches for animals.
At least, not usually. This image (3) shows a pair of German soldiers sheltering in a dugout with their horse.
The Army Veterinary Corps kept the casualties from escalating. It treated two and a half million cases, and returned 80% of them to active service. (4) So exemplary was its contribution to the “reduction of animal wastage, an increased mobility of mounted units and a mitigation of animal suffering” that King George V conferred the prefix Royal upon the Corps. (4)