The term ‘Celt’ is a generic one, applied to a group of northern European Indo-European tribes with a shared language and culture. Warfare was a large part of that culture, and the Celts were renown for their ferocity and bravery. They were regarded as a plague by the Romans until they finally subdued them. But even so, the army of Rome was not above using Celtic mercenaries and auxiliaries in the military.
The Celts first make their appearance in written history in 390BC when a group from Gaul attacked the Etruscans in the Po valley. The Romans were called in to negotiate between the two sides. During the talks, the Roman emissary killed one of the Gaulish leaders. Outraged, the Celts demanded the death of the murderer. When the Senate refused, the Celts besieged Rome. They invaded the city and besieged the Romans on the Capitoline Hill. They only left when the defeated Romans paid a high ransom.
Terror and intimidation seemed to be the key Celtic tactics. Polybius, writing of Celts in the second century AD, describes their enemies as: “terrified by the fine order of the Celtic host, and the dreadful din, for there were innumerable horn -blowers and trumpeters, and…the whole army were shouting their war-cries…Very terrifying too were the appearance and the gestures of the naked warriors in front, all in the prime of life and finely built men, and all in the leading companies richly adorned with gold torcs and armlets.”
So appearance and behavior played a part in Celtic tactics. The furor celtica as the Romans called it saw the Warriors’ race headlong into the fight, wild with battle rage. But it would be wrong to assume that Celtic battle tactics were haphazard. Chariots, in particular, were utilized skillfully in combat. The Celtic chariot was lightweight and had a flexible rope suspension that made it easy to steer and drive along rough terrain. These chariots could be driven skillfully into the midst of battle, allowing warriors to throw spears and intimidate the enemy infantry or else jump down and join the fray.
By the time of the death of Emperor Trajan in 117AD, the Roman empire was the largest in the ancient world, stretching from Spain to Syria, from the Adriatic to Britain. The empire had humble beginnings in a small settlement of herders and bandits living along the river Tiber. But its military had made it great.
Discipline, organization, and engineering were crucial to the Roman military as was the ability to adapt and amend and improve upon other people’s ideas. The Romans modeled their infantry on the Greek hoplites the Romans encountered amongst the Campanian Greeks. The Roman version was named legions, from legio, the levy or small allowance paid to each infantryman on active service. It was the legions who were the backbone of the short annual campaigns against neighboring Italian states which formed the germ of Rome’s empire.
But the real innovations to the army occurred after the Punic wars. Combat was now longer – and occurring away from Italian soil. By 201BC, after the final defeat of Carthage, it was evident the old army model would no longer serve Rome. So criteria for armed service was extended. All citizens between the age of 17-46 were eligible to serve in the army, regardless of property ownership. When they signed up, they agreed to serve in 6 consecutive campaigns and to enlist for 16 years- or 10 if they were in the cavalry.
Available manpower again increased after the Social Wars as the Romans extended citizenship to the conquered Italian states. The Roman’s continued with their policy of absorption as their territories expanded. Foreign units were added as auxiliaries, each bringing their unique fighting skills to serve the glory of Rome. For this was the Roman army’s key strength: teamwork. The achievement of the individual counted for nothing. Each soldier was a cog in the military machine. Discipline was tight, and soldiers fought in close formation rather than as individuals. This meant that Roman lines held in the face of fierce barbarian attacks.
Attacks were also very precisely planned. Battles began with a flight of javelins towards enemy lines. The intention here was to disable the enemies shields. A shield penetrated by a spear was useless defensively. So when the legions moved into close quarter combat, it was easier to cut down the enemy with their short sword, the gladius. Cavalry supported the legions by attacking from the rear and chasing down survivors. Siege weapons were also necessary. As well as battering rams and siege engines, the Romans developed the onager, an early form of a giant catapult which hurled huge boulders at stone walls or iron bolts into enemy lines.
Formed from the Achaemenid Persians and Scythian inspired nomads, the Parthian military bore a resemblance to the military societies of the Middle Ages. Dominated by heavy cavalry, who were accompanied by lightly armored horse archers, it only used infantry in times of protracted war. The Parthians adopted these tactics after their defeat at the hands of Alexander the great. They realized that only heavily armored cavalry stood a chance against the hoplite infantry. So they developed a system where the cavalry broke into the ranks of enemy infantry, causing them to scatter so they could be picked off by the lightly armored bowmen.
The Parthian archers were particularly renown for one particular skill: the Parthian shot. When in retreat- real or by design, the Parthian mounted archers s would send their horses into a full gallop. They would fully turn their bodies around in the saddle, so they faced the enemy and then fired upon them. This was achieved without stirrups for support, using just the knees pressed against the saddle to support the rider.
However, horses were themselves vulnerable in battle. So the Parthians took measures to protect them by providing the horses themselves with armor. Cassius Dio describes how the Parthians covered their horses with light metal armor that covered their “head, neck, chest and sides.” This light, flexible mail, made from overlapping leafs of metal was light and flexible enough not to impede the horse’s movement but still made it harder to bring the rider by injuring the horse.
Using these means, the Parthians were able to claim Iran back from the Seleucid Empire. Then came their encounters with the Romans. At the battle of Carrhea in 53BC, Parthian forces consisting of 1000 heavy cavalrymen and over 9000 horseback archers defeated the Roman general Crassus. Using their cavalry to scatter the Roman forces, the Parthians were able to defeat the Romans- despite the fact they were greatly outnumbered. The occasion marked the beginning of three centuries of conflict between Rome and the Parthians- until the Parthians themselves succumbed to another empire.