War horses came in three sizes, each trading speed for carrying power
A horse can carry roughly 30 percent of its own weight, but pulling a wheeled load on a paved road it can shift about eight times its weight. That simple gap shaped millennia of warfare, deciding which animals drew chariots and cannon and which carried armoured riders into battle.
Horses first joined warfare in Eurasia somewhere between 4000 and 3000 BC, and a Sumerian image from 2500 BC shows some kind of equine hauling wagons. Better harness and chariot designs made chariot warfare widespread across the Ancient Near East by 1600 BC, and the oldest surviving training manual for war horses, written around 1350 BC, dealt with chariot teams. Cavalry later displaced chariots, and around 360 BC the Athenian horseman Xenophon produced a detailed guide to horsemanship. The saddle, the stirrup and the horse collar each changed what mounted forces could do.
Horsemen follow the rule of form to function. Light breeds such as the ancestors of the Arabian, Barb and Akhal-Teke stood roughly 12 to just under 15 hands and weighed some 360 to 450 kilograms, ideal for raids, light cavalry and two-man chariots used by peoples from the Egyptians to the Mongols. Medium horses, which the Scythians were among the first to breed, spanned the widest range of sizes and carried armoured riders; the larger ones became the medieval destrier. Heavy animals of 680 to 910 kilograms, forerunners of today's draught breeds, hauled supply wagons and stayed calm under fire.
Hitching mattered too: a horse collar let an animal pull more than a breast collar, and an ox yoke least of all. Some riders travelled on a fast light mount and switched to a heavier one only when armoured for combat.
Nomads of the steppes built whole strategies around horses, Muslim armies relied on light cavalry from the 7th century, and after the armoured knight faded with gunpowder, light cavalry rose again, proving crucial in the Napoleonic Wars and the American Civil War. Ponies served as well: the British Army took 200 Dales ponies as pack animals in World War II, and a 1935 trial found Dartmoor ponies better than mules. Tanks replaced cavalry after World War I, and mounted units now mostly patrol or perform ceremonies.
Source: Horses in warfare
