The Untold Heroes of WWI: Animals That Served, Suffered, and Saved Lives

Between 1914 and 1918, more than sixteen million animals served in World War I. They pulled artillery through mud, carried wounded soldiers, delivered messages under fire, and detected poison gas before any human could. While tanks and airplanes introduced a new era of warfare, the war’s daily machinery ran on the backs of animals. They did not volunteer, yet they died in the millions.

At the war’s start, the cavalry was still considered a primary combat force. Soldiers rode into battle with swords and lances. That changed fast. Machine guns and entrenched defensive lines made cavalry charges suicidal. Horses shifted from frontline fighters to the war’s most essential transport workers. The British Army alone used over one million horses and mules across the conflict, most of them purchased from the United States and Canada and shipped across the Atlantic.

Horses hauled artillery pieces into position through deep mud that stalled motorized trucks. They pulled wagons loaded with food, ammunition, and water to the front-line trenches. Where roads ended and mountain paths began, mules took over. Sturdier and more patient than horses, mules carried heavy loads on their backs through terrain that no wagon could cross.

The cost was enormous. Approximately eight million horses died during the four years of fighting — from exhaustion, disease, and enemy fire. Engineers designed specialized gas masks that fitted over a horse’s muzzle to protect them from chemical attacks. Even with these measures, the losses were staggering.

Mules were shipped to every theater of the war. Armies from India, Egypt, and Australia relied on them just as heavily as the Europeans did. They appeared at ports, on mountain fronts, and deep in desert campaigns where horses could not survive.

Dogs served in several distinct roles, each saving lives in a different way. Messenger dogs were trained to navigate the chaos of the battlefield. When artillery fire cut telephone wires, these dogs ran through trenches and shell craters to deliver maps and orders. They were faster than human runners and presented a far smaller target to enemy snipers.

“Mercy dogs,” also called ambulance dogs, were trained to find wounded soldiers lying in No Man’s Land — the deadly open ground between opposing trenches. They worked at night or during lulls in the fighting, carrying small packs of medical supplies on their backs. A wounded soldier who could move would treat himself from the pack. If he was too badly hurt to move, the dog either stayed beside him or returned to the trenches carrying a piece of the man’s clothing to guide medics to his location.

Sentry dogs worked alongside guards, using their superior hearing and sense of smell to detect enemy patrols long before any human could. Some dogs were even fitted with harnesses to lay electric communication wire across the battlefield, a job that would otherwise expose a soldier to direct fire.

Sergeant Stubby of the 102nd Infantry became one of the most decorated war dogs of the entire conflict. He warned his unit of gas attacks, located wounded men in the field, and once caught a German spy by the seat of his pants and held him until soldiers arrived.

Carrier pigeons were the most reliable long-distance communication tool when every other system had failed. The military’s dedicated Pigeon Service deployed over 100,000 birds kept in mobile lofts that moved with the front lines. Soldiers carried the birds in small wicker baskets strapped to their backs, or transported them in tanks and airplanes. When a unit was cut off, they released a pigeon with a coded message attached to its leg.

Pigeons delivered their messages at a success rate above 95 percent. The most famous was Cher Ami, who saved nearly 200 American soldiers known as the “Lost Battalion.” Shot through the chest and missing a leg, Cher Ami still flew twenty-five miles to deliver the message that stopped friendly artillery fire from killing the surrounded men.

Smaller animals played technical roles that are largely forgotten today. Cats in the trenches controlled the massive rat populations and served as early warning systems for gas attacks, showing signs of distress before soldiers detected anything wrong. In the tunnels miners dug beneath enemy lines, canaries and white mice detected carbon monoxide and other deadly underground gases. If a canary fainted, the miners evacuated immediately.

Glow-worms were collected by the thousands and placed in glass jars. In the dark of the trenches, a lit match could draw a sniper’s bullet, but the faint light from a jar of glow-worms let a soldier read a map or a letter safely. Slugs provided another unexpected form of protection. Researchers discovered that slugs sealed their breathing holes and compressed their bodies when mustard gas was present — long before a human nose detected anything — giving soldiers extra seconds to put on their gas masks.

Many units adopted animal mascots to help cope with the psychological weight of the war. These were not always common pets. Some units kept monkeys, bears, or even lions. A Canadian soldier brought a bear cub named Winnipeg to England. The bear eventually lived in the London Zoo and became the direct inspiration for the character Winnie-the-Pooh. Mascots were given military ranks, small uniforms, and treated as full members of their units. In the long stretches of waiting between battles, they were often the only source of comfort available.