A single soldier on his horse, during a cavalry patrol in World War I. At the start of the war every major army had a substantial cavalry, and they performed well at first. However, the development of barbed wire, machine guns and trench warfare soon made attacks from horseback far more costly and ineffective on the Western Front. Cavalry units did prove useful throughout the war in other theatres though, including the Eastern Front, and the Middle East. #

Gas attack on the West Front, near St. Quentin 1918—a German messenger dog loosed by his handler. Dogs were used throughout the war as sentries, scouts, rescuers, messengers, and more. #

German soldiers pose near a horse mounted with a purpose-built frame, used to accommodate a captured Russian Maxim M1910 machine gun complete with its wheeled mount and ammunition box. #

A pigeon with a small camera attached. The trained birds were used experimentally by German citizen Julius Neubronner, before and during the war years, capturing aerial images when a timer mechanism clicked the shutter. #

Unloading a mule in Alexandria, Egypt, in 1915. The escalating warfare drove Britain and France to import horses and mules from overseas by the hundreds of thousands. Vulnerable transport ships were frequent targets of the German Navy, sending thousands of animals to the bottom of the sea. #

Sergeant Stubby was the most decorated war dog of World War I and the only dog to be promoted to sergeant through combat. The Boston Bull Terrier started out as the mascot of the 102nd Infantry, 26th Yankee Division, and ended up becoming a full-fledged combat dog. Brought up to the front lines, he was injured in a gas attack early on, which gave him a sensitivity to gas that later allowed him to warn his soldiers of incoming gas attacks by running and barking. He helped find wounded soldiers, even captured a German spy who was trying to map allied trenches. Stubby was the first dog ever given rank in the United States Armed Forces, and was highly decorated for his participation in seventeen engagements, and being wounded twice. #

An Indian elephant, from the Hamburg Zoo, used by Germans in Valenciennes, France to help move tree trunks in 1915. As the war dragged on, beasts of burden became scarce in Germany, and some circus and zoo animals were requisitioned for army use. #

"These homing pigeons are doing much to save the lives of our boys in France. They act as efficient messengers and dispatch bearers not only from division to division and from the trenches to the rear but also are used by our aviators to report back the results of their observation." #

Belgian Army pigeons. Homing pigeon stations were set up behind the front lines, the pigeons themselves sent forward, to return later with messages tied to their legs. #

Two soldiers with motorbikes, each with a wicker basket strapped to his back. A third man is putting a pigeon in one of the baskets. In the background there are two mobile pigeon lofts and a number of tents. The soldier in the middle has the grenade badge of the Royal Engineers over the chevrons which show he is a sergeant. #

A message is attached to a carrier pigeon by British troops on the Western Front, 1917. One of France's homing pigeons, named Cher Ami, was awarded the French "Croix de Guerre with Palm" for heroic service delivering 12 important messages during the Battle of Verdun. #

General Kamio, Commander-in-Chief of the Japanese Army at the formal entry of Tsing-Tau, December, 1914. The use of horses was vital to armies around the world during World War I. #

On the Western Front, a dead German artilleryman and several draft horses, ca. 1918. Exact figures are hard to come by, but an estimated 8 million horses died during the four years of war. #

Horses requisitioned for the war effort in Paris, France, ca. 1915. Farmers and families on the home front endured great hardship when their best horses were taken for use in the war. #

Dead horses and a broken cart on Menin Road, troops in the distance, Ypres sector, Belgium, in 1917. Horses meant power and agility, hauling weaponry, equipment, and personnel, and were targeted by enemy troops to weaken the other side -- or were captured to be put in use by a different army. #

War animals carrying war animals -- at a carrier pigeon communication school at Namur, Belgium, a dispatch dog fitted with a pigeon basket for transporting carrier pigeons to the front line. #