At the beginning of the war the British Army owned 25,000 horses. This was not considered enough and during the next two weeks a further 165,000 were recruited from Britain. Horses were also purchased from the USA, New Zealand, South Africa, India, Spain and Portugal. Horses aged three to twelve were trained as rapidly as possible by British soldiers called 'roughriders'. When they were ready the horses were formed into squadrons and sent to the Western Front.
The best horses were used by the cavalry. These horses had to be strong as the average cavalryman's weight was twelve stone and his equipment, saddle, ammunition, etc. usually weighed another nine stone. Men in the cavalry were instructed to take the weight off their horses as much as they could. This including dismounting and walking with their horses and unsaddling at every opportunity.
In 1914 the British Army only owned eighty motor vehicles. Therefore they were very dependent on horses for transporting good and supplies. This was especially true of the Western Front where conditions made it very difficult to use motor vehicles.
The British Army also purchased a large number of mules from the USA. The mule has amazing stamina and endured the terrible conditions in the front-line better than the horse. At the end of the war the army owned 213,300 mules.
Finding enough food for the horses and mules at the Western Front was a constant problem. The daily ration for a horse was 20 lbs of grain a day. This was nearly 25% below what a horse would be fed in Britain. The horses were always hungry and where often seen trying to eat wagon wheels. When grain was in short supply, the army fed their horses and mules on sawdust cake.
Lieutenant Dennis Wheatley described the high casualty rate of horses on the front-line in 1915: "There were dead ones lying all over the place and score of others were floundering and screaming with broken legs, terrible neck wounds or their entrails hanging out. We went back for our pistols and spent the next hour putting the poor, seriously injured brutes out of their misery by shooting them through the head. To do this we had to wade ankle deep through blood and guts. That night we lost over 100 horses."
Brigadier-General Frank Percy Crozier took part in the Battle of the Somme: "If the times are hard for human beings, on account of the mud and misery which they endure with astounding fortitude, the same may be said of the animals. My heart bleeds for the horses and mules."
By 1917 the British Army were employing over 530,000 horses and 230,000 mules. Large numbers of horses were killed and wounded during the war. Others became lame or sick. The British Army discovered they needed to buy about 15,000 horses a month to maintain the number they needed. It has been calculated that almost half a million horses owned by the British Army were killed during the First World War.
At the end of the war General Douglas Haig wrongly believed that horses would continue to be used in warfare: "I believe that the value of the horse and the opportunity for the horse in the future are likely to be as great as ever. Aeroplanes and tanks are only accessories to the men and the horse, and I feel sure that as time goes on you will find just as much use for the horse - the well-bred horse - as you have ever done in the past."