“hi, cum est usus atque aliquod bellum indicit – quod ante Caesaris adventum fere quotannis accidere solebat, uti aut ipsi iniurias inferrent aut inlatas propulsarent -, omnes in bello versantur . . . ”

“Whenever the need arose and a war broke out – which as a rule happened every year before Caesars arrival that they either opened up hostilities themselves or had to defend against -, they all joined the battle . . .” (Caesar, De Belli Gallico VI – 15,1)
Caesar may be a biased source, but his statement tells us a lot about the role of war in ancient Celtic society: it was an important part of life, primarily for the nobility, but, to a lesser degree, also for the average man. We see a similar picture if we take a look at the Irish or Welsh legends, where the heroes go off to fights, most often one at a time or in small groups, but often in the company of their followers and clients to fight mass battles.
A Short, Short History of Celtic Expansion and Retreat
Before we look into ancient Celtic warfare itself, it is necessary to define what time and geographical region I will be talking about. Even though Celtic culture developed probably some centuries earlier, the oldest material I’ll be discussing dates to the beginning of the 5th century BC in central Europe. From that point, the culture expanded until, in the 3rd century BC, it reached its greatest extent with Celts living in Ireland and Spain in the West and as far as Galatia in Asia Minor in the East. This was partly due to cultural exchange and peaceful transmission of ideas, partly due to massive military campaigns like that in northern Italy. From then on, however, the Celts began to lose ground. Starting even in the 3rd century BC, the Romans began to conquer the Celtic lands From the South . Only a little later, Germanic pressure increases from the Northeast. By the end of the 1st century BC, all the Celtic lands but the British Isles were conquered either by the Romans or had become germanised, either by a similar cultural exchange (like that when they became Celtic) or by force of arms. Most of Britain comes under Roman control less than a century later, leaving only what is modern Scotland and Ireland as Celtic territory. The end of what I think of as ancient Celtic culture came when Ireland was christianised in the 5th century BC, followed by Scotland soon after.
“Typical” Celtic Warrior
To start with, the typical Celtic warrior was male. Even hints that armed females existed are extremely rare. Not a single instance of a female burial containing a shield or a sword has yet been uncovered. About 50 percent of the males, about 25% of the total population, were buried with weapons. Caesar, in his report about the Helvetian census, tells us that of about 350,000 people about 90,000 carried arms, which amounts to about 25% of the Helvetian population that decided to move into Gaul.
A Celtic warrior’s basic equipment consisted of a set of one to four spears. One was a 1.8 meters long fighting spear called a “lancea” that sometimes had very large spearheads of up to 50 centimetres in length. The others were shorter throwing spears called “gaesum” with relatively small, normally shorter than 10 centimetres long spearheads. A warrior also had a large—about 1.2 meter high and 0.5 meters wide—leather-covered, wooden shield with a metal shield-boss. This was likely to have been decorated with painting and sometimes metal ornamentation. With this basic equipment, the average warrior usually wore his everyday clothing consisting of trousers, a shirt, and a mantle.
A must for the Celtic noble, besides his torc (neck ring), was a long-sword with a blade-length of about 0.8 to 1 meter. Those from the early period had definite swordpoints, enabling them to be used for slashing and piercing. In the later period, these swords often had rounded points that allowed only slashing attacks. In rare cases, especially in finds from the eastern Celtic world, such swords had anthropomorphic handles, the pommel most often cast from bronze in the form of a human head. Additionally, the typical noble warrior probably wore armor and helmet, all made from leather. Depending on how rich they were, nobles might have equipment such as helmets, made from bronze or iron, often elaborately decorated with ornamentation and inlays of coral or even gold. Occasionally, the helmet might have additional embellishments such as the one from the famous find at Ciumesti, Romania, which has a figure of a raven with mobile wings fixed to its crest. That helmet must have been an impressive sight when the owner moved down the battlefield. Chainmail suits, covering the body down to the knees and, most often, leaving the arms free, were very rare, and, obviously affordable by only the wealthiest nobles
The Celtic Battle-Chariot
Even though it was not used always and everywhere in the Celtic world, the battle-chariot is considered a very typical part of Celtic warfare. It was called a “carpentom” or similar term, and was a light, two-wheeled vehicle drawn by a pair of yoked horses, little more than four meters in length and less than two meters wide. The chariot consisted almost exclusively of organic material; the main metal parts were the iron tires and the iron fittings to strengthen the hubs. In some cases, metal rings and connectors were used to strengthen joints and flexible connections. What made the Celtic chariot so special, however, was that the chariot-platform was not fixed to the axle but hung free in a rope suspension. This made it a lot more comfortable to drive and a lot easier to fight from.
Usually two persons rode in the chariot. The charioteer sat in the open front of the chariot and actually drove. The warrior stood behind the charioteer and threw his spears from the chariot before alighting and fighting on foot. The charioteer stayed close enough to retrieve his warrior and carry him away from the battle if he were wounded or killed. This system is well documented in the Irish Ulster Cycle, as well as in the works of Roman and Greek historians.
Celtic Warrior Bands
Also quite typical among the Celts were warrior-bands like the Irish fianna or the Gaesates who fought in the Italian Wars against the Romans. Such warbands consisted mainly of young men led by charismatic leaders like the Irish Fionn Mac Cumhaill or the two kings of the Gaesates. The latter seem to have been used as high response troops in battle, according to the Roman sources. Most probably these groups had a religious dimension, requiring various initiation rituals for membership. They most probably enjoyed a special status in Celtic society. Members of these warrior bands probably were known for performing heroic feats. For example, historians recorded that the Gaesates fought naked in the battles in the Po valley in Italy where the Cisalpine Celts opposed the Romans. Most notably these warbands seem to have consisted mostly or even exclusively of infantry.
The Nature of Celtic Warfare
The Celts fought many battles. Some involved rather small numbers of combatants, but there were also mass battles in which at least tens of thousands or perhaps even hundreds of thousands participated, if we believe the numbers reported by various ancient historians. However, in contrast to the rigid Roman military organisation, Celtic warriors seem to have been much less used to fighting in formations and organized units. The records we have from ancient historians paint the picture of mostly unorganised groups. The ancient Celtic warriors engaged their enemy as if they would defeat them simply by overrunning them, trusting their brute force more than elaborate tactics and clever strategies. This may well be due to a trait of Celtic mentality, which valued individual prowess with arms and heroic feats more than fighting in tight groups and trusting in the combined power of many men in close military formations.
Military organisation seems to have been based, in case of the infantry, more on where one came from than the type of weapons one carried, although chariots and/or cavalry were set aside to fight together. The warbands, who were most likely the high response troops of the Celts, often formed the first line of the infantry, hurling themselves upon the enemy in the first assault.
In battles, the Celts also made use of what has been dubbed “psychological warfare.” Before actually engaging the enemy, they are said to having made a horrible noise by clashing their weapons against their shields, crying and singing, with horns (carnyx) being blown and maybe drums being beaten. In the early period, these practices, together with the wild onslaught by the first lines of warriors, seems to have shocked Roman troops so that much that they simply gave way and fled from the field in fear for their lives. Also, before the actual fight, the Celtic war leaders paraded in front of their troops, performing heroic feats, proclaiming their own deeds, belittling their enemies, and challenging enemy leaders to duels. The results of these individual combats were apparently regarded as omens of the outcome of the battle.
However fierce that first onslaught, the ancient Celts had, according to the ancient historians, little endurance. If their first assault didn’t succeed, the Celtic forces were easy to defeat, or so the historians say. On the other hand, the historians might have been perpetuating the image of the Celts as barbarians by ascribing superior physical strength but less endurance to them, especially since endurance was regarded as one of the primary Roman virtues. Evidently, to actually defeat the Celts was not as easy as the ancient historians wanted their readers to believe, since quite a number of reports tell us that the Celts continued to fight valiantly to the end, even when the battle already was lost. Often the Celts were depicted as killing themselves and their close relatives rather than surrendering and being sold into slavery.

However, the most of the battles seem to have been rather small, involving only a few warriors on both sides. Most probably they occurred as a result of raids on neighbouring tribes, such as the raids mentioned by Caesar in the quote at the beginning of this essay, or in the Irish story of the cattle raid of Cooley. Raiding was a practice well-attested for the Irish as late as the 15th century CE. Of course, if such a raiding party were intercepted, a battle would result. We also should assume that raids were not limited to cattle but could well have targeted other valuables or slaves. Such raids, of course, brought retribution which could, of course, lead to larger military operations. Most such raids and military operations probably were taken up in late spring, when weather and agricultural necessities allowed for small and large military operations to take place.
Famous Battles and Statements of Ancient Celtic Warriors
During history, the Celts fought a number of famous battles that have been recorded by historians and, as such, have come down on us.
Immediately after their first appearance in written history, Celts came into military conflict with the Mediterranean world. After moving into the Po valley, they pushed back the Etruscans after probably defeating them in some battles. The Celts then celebrated what was probably their most famous victory. During a military campaign of the Celts against an Etruscan city in the year 390 or 387/386 BC, the Romans were called in as negotiators. During the talks, a Roman emissary killed one of the Celtic leaders. Understandably enraged, the Celts sent emissaries to Rome demanding that the murderer be handed over to them, but the Roman Senate decided not to heed their request. Upon hearing this, the Celts decided to march on Rome, defeated a Roman army on their way, and entered the city of Rome. The Romans had decided not to defend the city, but instead had retreated to the Capitol hill. The Celts lay siege to this hill for some time, until the Romans agreed to pay a high ransom. When the sum was collected, the Romans complained about the Celtic scales, claiming that they were not properly balanced. At this, a certain Brennos, leader of the Celtic army, threw his sword on the scales and exclaimed, “Vae victis” (Woe to the defeated). This defeat severely affected the Roman psyche, instilling a fear of Celtic troops marching on Rome that led them to take extreme measures as late as the 3rd century AD, when independent Celts had ceased to exist everywhere but in Scotland and Ireland, far away from Rome.
Alexander the Great encountered Celts when he arrived in the lower Danube during his campaign on the Balkans in the second half of the 4th century BC. On this occasion was made the famous statement that the Celts feared nothing but that the heavens might drop on their head; Alexander had expected to hear that they feared his military might.
In the early 3rd century BC, the Celts appeared in Greece, again led by someone named Brennos. The Celts attacked Delphi which, according to the sources, was defended successfully only because an earthquake hindered the Celts. The leader Brennos asked his close friends to kill him after he was seriously wounded in the battle. The bulk of the Celts retreated back north, but a group of them split off and crossed the Dardanelles to Asia Minor, where, after fighting a number of battles, they settled in central Anatolia.
From then on, however, the Celts were on the losing end. Northern Italy was lost during the 3rd century AD in a number of consecutive battles, the most famous of which probably was the one at Telamon in 225 BC. Though the Gaesates fought valiantly, the Celts were defeated.
In the years 58 to 52 BC Roman legions, led by Julius Caesar, conquered Gaul. In his commentary De Bello Gallico, Caesar described a number of battles that took place during this war. In the last years of the war against Rome, the Gauls more or less united under the leadership of an Avernian noble named Vercingetorix. Though Vercingetorix won some battles against Caesar (who was barely able to save his own life in the battle of Gergovia in 52 BCE), but he was finally defeated in the battle of Alesia in the same year. This effectively ended Gaulish independence.
In the second quarter of the 1st century AD the Romans conquered Britain as part of a number of relatively limited battles. The last of the famous Celtic battles for which there are records happened in Britain. First there was the rebellion under the leadership of Icenian queen Boudicca in 61 CE. Finally in the year 83 or 84 CE, the battle at Mount Graupius, assumed to be as far north as near Aberdeen in Scotland, where the Celts were defeated. This battle was the last time the Romans recorded encountering use of the Celtic chariot in battle.
From Ireland, the only records of battles are the myths, such as cattle-raid of Cooley in the Ulster Cycle. Since these are related only in the myths, we cannot be sure whether they were actual historical battles or completely belong to the realm of legend.
Conclusions
War and warfare definitely played an important role in ancient Celtic society. The nobility most probably was a warrior elite that spent considerable time training with weapons. For them, fighting and raiding were quite common occurrences. The client landowners most probably were also required to fight if and when the need arose, both to defend their own land and to attack enemies. Since they were involved in the production-cycle, they probably did not have as much training as the nobility and probably were less often involved in actual military conflicts.