Ancient cavalry spurs

Early spurs had a neck that ended in a point, called a prick, riveted to the heel band. The spur was used by the Celts during the La Tène period (which began in the fifth century BCE), and is also mentioned by Xenophon (circa 430 - 354 BCE.) in his treatise "On Horsemanship".  

When the horse is about to leap over any obstacle, Xenophon recommends applying the spur on takeoff, so that the horse will use his whole body over the obstacle and make a safer jump. If this is not done, Xenophon points out, he may lag with his hind end. Xenophon goes on to admonish those wishing to make a horse "showy" to spare the spur. He emphasized that the rider should not pull on the bit nor spur or whip the horse, as this type of riding causes the opposite effect, simply distracting and frightening the animal and causing him to dislike being ridden. Instead, Xenophon urges, the horse must enjoy himself. He should be trained to be ridden on a loose rein, to hold his head high, arch his neck, and paw with his front legs, taking pleasure in being ridden.

Despite Xenophon's reputation for equestrian knowledge, however, the famed Companion Cavalry of Alexander the Great did not use spurs, bit, or stirrup. 

Bronze spurs have been found in Etruscan tombs dating to the 2nd century BCE, though, and iron or bronze spurs were used by Julius Caesar's auxillia cavalry, as evidenced by archaeological finds in England, and, later, throughout the Roman Empire. 

Some examples of Roman period spurs have been found in bogs and thought to have been offered by Germanic populations as a sacrifice to the gods, along with other war booty, after a successful battle. 

Germanic or Gallo-Roman prick spur, 2nd - 3rd century CE

Bronze Celtic spur from about 300 BCE courtesy of horsefactbook.com

More simple spur from a Roman military workshop in Aquincum, a Roman municipium north of modern Budapest, Hungary, 2nd century CE, courtesy of Wikimedia Commons contributor Bjoertvedt