But the new weapons of war proved devastating to the cavalrymen and their mounts. This war was was demarcated by inpeneterable barbed wire. Machine guns massacred man and horse alike with little or no direct contact with their enemies. The horse s utility in battle was over. The death of millions of horses in this war drastically reduced the world's equine population.
Some estimates hold that six million horses served in the war zones of American troops.
Most of them were killed. In the four years of the war, the United States was left with a seriously depleted stock of horses in America. The American Expeditionary Force took with it an additional 182,000 horses to the battle lines. British veterinarians treated 120,000 horses for wounds or disease in aftermath of the battles. With the newly developed weaponry one fact remained painfully obvious, the horse was the innocent victim.