Fire support was deemed particularly important for the proper deployment of cataphracts. The Parthian army that defeated the Romans at Carrhae in 53 BC operated primarily as a combined arms team of cataphracts and horse archers against the Roman heavy infantry. The Parthian horse archers encircled the Roman formation and bombarded it with arrows from all sides, forcing the legionaries to form the Testudo or "tortoise" formation to shield themselves from the huge numbers of incoming arrows. This made them fatally susceptible to a massed cataphract charge, since the testudo made the legionaries immobile and incapable of attacking or defending themselves in close combat against the long reach of the Parthian cataphracts' kontos, a type of lance. The end result was a far smaller force of Parthian cataphracts and horse archers wiping out a Roman army four times their number, due to a combination of fire and movement, which pinned the enemy down, wore them out and left them vulnerable to a deathblow.