Military animals are trained animals that are used in warfare and other combat related activities. As working animals, different military animals serve different functions. Horses, elephants, camels, and other animals have been used for both transportation and mounted attack. Pigeons were used for communication and photographic espionage. Many other animals have been reportedly used in various specialized military functions, including rats and pigs. Dogs have long been employed in a wide variety of military purposes, more recently focusing on guarding and bomb detection, and along with dolphins and sea lions are in active use today. Horses in warfareDogs in warfareWar elephantWar pigWar pigeonCamel cavalry and Moose cavalry The horse was the most widely used animal throughout the recorded history of warfare. Early mounts could pull a chariot or carry lightly armored skirmishing forces. With the appearance of heavier mounts and the invention of the stirrup, the horse-mounted cavalry became the most prestigious combat arm in Europe for several centuries. A knight's warhorse was trained to bite and kick. The combination of the horse-mounted warrior armed with a bow made the steppe people's armies the most powerful military force in Asian history. Horse-drawn war wagons were used by the Hussites during the Hussite Wars. With the appearance of modern ranged weapons and motor vehicles, horse use for military purposes fell into decline. However, horses and mules are still used extensively by various armies today for transport in difficult terrain. While elephants are not considered domesticable, they can be trained to serve as mounts, or for moving heavy loads. Sanskrit hymns record their use for military purposes as early as 1,100 B.C. A group of elephants was employed by Hannibal during the Second Punic War. They were employed as recently as World War II by both the Japanese and Allies. Elephants could perform the work of machines in locations where vehicles could not penetrate, so they found use in the Burma Campaign.