Celtic Arms & Armor

The main sources of evidence about ancient Celtic arms and armour come from archaeological finds, Greek and Roman literary accounts, and art depicting Celtic warriors. The main Celtic weapons would have been a sword, usually fastened on the right side and a spear. The normal means of protection was the shield, but sometimes helmets were worn and less often tunics of ring mail.

Celtic Iron Swords

Celtic warriors were primarily thought of as swordsmen in the ancient world and would often fight on the sides of Ancient Greeks and Romans throughout antiquity as mercenaries.

These are the creatures who assail you with such terrible shouts in battle, and clash their arms and shake their long swords and toss their hair.

Appian, History of Rome: Gallic Wars

Iron swords in sheaths of iron, bronze, wood, or leather were the symbol of the warrior and as such were often personalized by elaborate decoration applied to the sheath or by stamps beaten into the blade.

The bronze and iron swords of the early Celts of the Halstatt period were similar in design. There was a period when both were used for the same time. The stronger iron weapons were used by elite troops. Hallstatt swords could be very big and long, suggesting they were mainly used as slashing weapons, although they also had a definite sword point so would have been able to be used for piercing attacks. Towards the end of the Hallstatt period, around 600–500BC, swords were replaced with short daggers.

The La Tene culture reintroduced the sword as the Celts spread over their vast range, having conquered most of Europe at their height, their warriors developed different styles of warfare. In Spain, they became master swordsmen accustomed to up-close combat with their short swords. In southern Gaul they developed impressive armour and preferred long swords. Some swords in the late La Tene period often had rounded points that allowed only slashing attacks.

they carry long broad-swords which are hung on chains of iron or bronze and are worn along the right flank.

Diodorus Siculus, Library of History, Book 5, Chapter 30

Swords were normally worn on the hip or side, hanging from a bronze or iron chain. However among the Parisii of Yorkshire, for example, the sword was sometimes worn across the back and had therefore to be drawn over the shoulder from behind the head.

Quality of Celtic Swords

Polybius is scathing of the quality of the swords used at Telamon in the third century. They were good for cutting but not thrusting and became easily bent during battle, requiring the warriors to pause and bend them back into shape with the foot, he reports.

from the way their swords are made, as has been already explained, only the first cut takes effect; after this they at once assume the shape of a strigil, being so much bent both length-wise and side-wise that unless the men are given leisure to rest them on the ground and set them straight with the foot, the second blow is quite ineffectual.

Polybius, The Histories Book 2, Chapter 33

While there was, indeed, a variation in quality, and some made of softer iron may have been ineffective, the description may owe something to the fact that swords were often deliberately bent before being ritually deposited and it may have been the results of ritual activity rather than battle that Polybius was noting.

Celtic Spears

Although the Gallic warrior is described by the ancient sources as predominantly a swordsman, for the poorer Gallic warrior the most fundamental part of his equipment was his spear. A warrior would be able to obtain a spear before a shield, sword or helmet.

Celtic spears were well known in the ancient world and there were four terms to denote these weapons; lancea, mataris, saunion and gaesum, although they probably only had two main functions, a throwing weapon and a thrusting weapon. A considerable variety of spearheads have been found, the different weights and shapes suiting them to different purposes. The larger spears can range up to 2.5m long, the heads being almost 0.5m alone. Smaller spears are assumed to be throwing javelins. 

A Celtic warrior’s basic equipment consisted of a set of one to four spears.

The Gaesum or madaris is a heavy Gaulish javalin with relatively small spearheads, normally shorter than 10 centimetres long.

Javalin – Lanciae or Mataris

The javelin was called a matara by ceasar, mataris by Livy and madaris by Strabo. From Virgil we learn that the two of these javelins were carried in the hand of each Gaulish warrior.

[O]utside besieging Gauls the thorny pathway climbed, ambushed in shadow and the friendly dark of night without a star; their flowing hair was golden, and their every vesture gold; their cloaks were glittering plaid; each milk-white neck bore circlet of bright gold; in each man’s hand two Alpine javelins gleamed, and for defence long shields the wild northern warriors bore.

Virgil, Aeneid, Book 8, line 630

Diodorus is probably referring to the same weapon when he uses the name saunian to the missile weapons of the Gauls, which they call the lancia.

The spears they brandish, which they call lanciae, have iron heads a cubit [45cm] in length and even more, and a little under two palms in breadth; for their swords are not shorter than the javelins of other peoples, and the heads of their javelins are larger than the swords of others.

Diodorus Siculus, Library of History, Book 5, Chapter 30

Isidore of Seville (c. 560 – 636 AD) wrote in his book of Etymologiae (study of the origin of words) defined the Lancea as by Isidorus as

Lancea est hasta amentum habens in medio: dicta autem lancea quod aequa lance, id est aequali amento, ponderata vibratur.

A lance (lancea) is a spear with a strap attached to the middle of its shaft; it is called lancea because it is thrown weighed equally in the ‘scales’, that is, with the strap evenly balanced.

Isidor,  Etymologiae, Book 18 War and Games, Chapter 7

The spears of the Gauls were not like javelins, but what the Romans called pila, four-sided, part wood and part iron, and not hard except at the pointed end.

Appian, History of Rome: Gallic Wars, 1

Thrusting Spear

The Gallic spear, intended for thrusting rather than hurling, is named by Stabo, who distinguishes it from the mataris or javalin. He implies it was a great length, being in proportion to the bodies of the Gauls and to that of their other weapon. It was probably the weapon of their cavalry and heavy armed infantry.

The Gallic armour is commensurate with the large size of their bodies: a long sabre, which hangs along the right side, and a long oblong shield, and spears in proportion, and a “madaris,”​ a special kind of javelin.

Strabo, Geog 4.4.3

The Romans described the spear of the Gauls with the word gaesum, a Latinisation of the Gaulish *gaisos.

Celtic Spear Heads

The large collection of spear heads recovered from the ritual site of La Tène presents a variety of lethal designs with serrated, flame-shaped, and hollow-ground blades designed for easy penetration. Early La Tène spearheads had gradually lengthened and narrowed. By the late La Tène, some of these objects measured over 60–80 cm long.

Diodorus Siculus also describes one spear, with a notched blade so that the blow not only cuts but also tears the flesh, and the recovery of the spear rips open the wound

Some of these javelins come from the forge straight, others twist in and out in spiral shapes for their entire length, the purpose being that the thrust may not only cut the flesh, but mangle it as well, and that the withdrawal of the spear may lacerate the wound.

Diodorus Siculus, Library of History, Book 5, Chapter 30

Spearheads were often attached to a wooden shaft by rivets through perforations on the socket, although some spearhead had none and were attached in another manner.

Celtic Spear Shafts

There are scarce remains of wooden shafts from the period, but it is known that during the Early Roman Empire they were made from ash and hazel because of the strength and flexibility of the wood compared to other species. One was a 1.8 meters long fighting spear called a “lancea” or “lanciae” that sometimes had very large spearheads of up to 50 centimetres in length.

Nominal mention here should be of the ‘Gáe Bolg’, possible meaning “gapped/notched spear” which comes from Irish mythology, and was the was the name of the spear of Cúchulainn in the Ulster Cycle. It was given to him by his martial arts teacher, the warrior woman Scáthach, and its technique was taught only to him.

Celtic Spear Butts

In La Tène cultural material, three types of butts exist: conical, a nail with a massive conical ending, and a combination of these two concepts. The butt as a constructional element had several functions: first, protection of the lower end of the wooden shaft when stuck in the ground; second, as a secondary point if the main one is damaged; and third, as a counterweight to achieve better balance when the spear was thrown.

Celtic Sling

The sling is only mentioned in passing and does not feature in any set-piece battle. Slings themselves do not survive, being made of leather, but their importance may be shown in two ways: firstly in the shape of hillfort defences in the first century BC in southern Britain, and secondly in the huge hoards of sling stones that were prepared in readiness for sudden attack at hillforts in the UK such as Maiden Castle, Glastonbury, All Cannings Cross, Gussage All Saints, Yambury Castle, Castell Henllys and Ham Hill. In Maiden Castle, for instance, huge stockpiles (22,260 stones) of carefully selected sling pebbles were found near the East Gate – the majority were beach pebbles of approximately 50 grams, but some were specially prepared in clay. The gates and earthworks of hillforts also seem to have been designed to facilitate the use of the sling to drive away attackers.

Caesar gives a detailed description of the siege tactics used by the people in northern Gaul during the late Iron Age:

The Belgae have the same method of attacking a fortress as the rest of the Gauls. They begin by surrounding the whole circuit of the wall with a large number of men and showering stones at it from all sides; when they have cleared it of defenders, they lock their shields over their heads, advance close up and undermine it [… ] with such a large force hurling stones and javelins, no one could possibly stay on the wall.

Caesar, Gallic Wars: 2.6

Celtic Bow and Arrow

The use of the bow by ancient Britons, probably for hunting, is proved by the frequent discovery of arrow heads beautifully formed of flint and delicately barbed. However there are no references to the use of the bow and arrow by the Britons in war.

We know the bow and arrows were used by the Gauls from references made by Caesar and Strabo.

Caesar mentions Vercingetorix found archers for his army. Presumably these archers were made up from the lower classes of Gallic society, although their presence in the battle played a more significant role than this rank would suggest. More than forty examples of arrowheads have been recovered from Alesia, with either one or two barbs, and many can be paralleled by examples coming from other Gallic oppida.

Celtic Shields

Celtic shields were used in battle by the Celts and other ancient tribes as their main means of defence. Pausanias says that the Celts had no other defensive armour than their national shields.

The Gauls were worse armed than the Greeks, having no other defensive armour than their national shields.

Pausianas, Description of Greece – Phocis and Ozolian Locri Chapter 21, Section 2

Boudica, exhorting her troops before battle, scorned the Roman helmets, breastplates and greaves, saying that the Britons believed that their shields gave greater protection than did the whole suits of mail of the Romans.

[Boudicca says] our shields as affording greater protection than their whole suits of mail.

Cassius Dio, Roman History, Book 5, Chapter 62 Section 5

Celtic shield were usually oval, but they could be rectangular, circular, or hexagonal.

The Wandsworth shield boss – Copper-alloy shield boss with repoussé ornament in the form of stylized bird-heads.
©British Museum (CC BY-NC-SA 4.0)

On the front was a boss or umbos – a metal cup to protect the hand behind, which was holding the handle.

The shields were made of wood (often oak) and stood about 1.1m high. They were about 1.2cm thick in the centre, and overall weighed about 6kg. They were covered with leather (or felt), as bare wood would splinter when struck with a weapon.

For armour they use long shields, as high as a man, which are wrought in a manner peculiar to them, some of them even having the figures of animals embossed on them in bronze, and these are skilfully worked with an eye not only to beauty but also to protection.

Diodorus Siculus, Library of History, Book 5, Chapter 30

The shields were usually decorated with various designs, which can be seen on stone carvings and other pictures. An idea of the variety of decoration favoured is provided by the piles of armour depicted on the Roman triumphal arch at Orange.

Detail of the roman Triumphal Arch in Orange, France @ Akke GNU Free 1.2

The simplest form of shield was made of leather or wood or a combination of the two. The ritual deposit found in a bog at Hjortspring on the Danish island of Als contained 150 wooden shields. They were made out of planks with circular holes to take handgrips, with the knuckles protected by wooden boss. Shields of this kind would have been effective but heavy. A shield found in a bog at Clonoura, Co. Tipperary, in Ireland would have been far more efficient as it was composed of a thin sheet of wood covered back and front with leather with the boss was also of leather. A similar type of shield was found in a burial at St Peter Port, Guernsey, with a boss of iron. In all probability this type was in widespread use, though usually only the metal fittings survive.

Ceremonial Celtic Shields

The Battersea Shield is one of the most significant pieces of ancient Celtic Art found in Britain. The decoration is in the typically British Celtic La Tène style, consisting of circles and spirals. There are 27 small round compartments in raised bronze with red cloisonné enamel.
© British Museum (CC BY-NC-SA 4.0)

The most famous Celtic shield is the Battersea shield, found in the River Thames at Battersea. Sometimes objects like shields and swords were thrown into rivers as offerings to a god. The Battersea shield is an amazing work of art, the most famous piece of Celtic art ever found in Britain. It is made of bronze and enamel (coloured glass). Originally it had a wooden back, but only the bronze is left now. However, it is too small (77cm high), fragile, and expensive, to have ever been used in battle, and was most probably just an offering.

 The Witham Shield
Copper alloy decorative front of a shield, originally fixed to a wooden or leather back. The shield has two roundels, a central spine and boss with La Tène decoration.
© British Museum (CC BY-NC-SA 4.0)

Celtic Helmets

La Tene helmets of various shapes and designs appear in graves from the 5th century BCE on. However, Celtic helmets are rare, and it is likely that helmets were not widely used by some tribes. Their scarcity backs up Greek and Roman claims that some Celtic tribes scorned the use of helmets. The only area where significant numbers of Celtic helmets have been found is Italy.

Copper alloy peaked Celtic helmet.
© British Museum (CC BY-NC-SA 4.0)

Bronze helmets were a feature of warrior equipment. In fourth-century Italy cast bronze helmets with top-knobs, known as ‘jockey caps’, were fashion able, some of which had check pieces.

Helmets decorated with animal motifs, no doubt including wings, were described by Diodorus Siculus as being worn by Celts.

Ceremonial Celtic Helmets

About 350 BC Musée d’Angoulême – This impressive piece of art was buried in a cave in Agris, western France. The entire cap, neck guard and cheek guards were all cluttered with lavish gold tendril and leaf design. Together with the gold, red coral inlays provide n effectual contrast.
Kunst der Kelten, Historisches Museum Bern. Rosemania (CC BY-SA 2.0)

Many surviving examples of Celtic helmets are ceremonial and were not intended for use in actual combat. These were status symbols, made with expensive materials like gold and coral in addition to bronze and iron. The often impractical designs indicate that they were intended to make the wearer more visible in parades or processions, rather than to provide protection in actual combat. Celtic helmets began to be less ornate and more practical in the later La Tene period, perhaps indicating that their use was becoming more widespread.

On their heads they put bronze helmets which have large embossed figures standing out from them and give an appearance of great size to those who wear them; for in some cases horns are attached to the helmet so as to form a single piece, in other cases images of the  fore-parts of birds or four-footed animals.

Diodorus Siculus, Library of History, Book 5, Chapter 30
Celtic helmet with a complete winged-bird crest from the 3rd century BC, found at Ciumesti, Romania
© Wolfgang Sauber (CC BY-NC-SA 3.0)

This is amply borne out in the archaeological record, with finds of helmets with sockets for projecting elements and, in the case of one helmet from Ciumesti in Romania, with an attached bird complete with wings hinged to the body to allow them to flap.

Waterloo Helmet © British Museum (CC BY-NC-SA 4.0)

The horned helmet recovered from the Thames at Waterloo Bridge is the only Iron Age helmet with horns ever to have been found anywhere in Europe. This helmet is unlikely to have been used in battle and was probably a form of ceremonial headdress.

Small castings of bronze boars found in many parts of Europe are most likely to have been helmet attachments. Boar-crested helmets as well as others with birds and horns are shown worn by the warriors depicted on the Gundestrup cauldron.

Celtic Armour

Diodurus comments that some of the Celts went into battle naked. This is probably true of the early period. Most of Diodorus’ description refers to the later period. At the battle of Telemon in 225 BC the Geasati, who crossed the Alps from Switzerland to fight on the Celtic side, were noteworthy to Polybius as they still fought in this fashion whereas the other Celts did not.

Padded Armour

Composite armour made of fabric or leather, not unlike the Greek linothorax, is portrayed in Celtic art and was certainly used. Mounted warriors depicted on a Halstatt scabbard from Grave 995 appear to be wearing a kind of padded tunic with a skirt of leather straps., known as pteruges in Greek to protect the lower body.

Halstatt scabbard from Grave 995

The 500 BC statues excavated from the Glauberg elite burials near Frankfurt in Southern Germany are glad in a padded linen cuirasses similar to those worn by Greek and Etruscan hoplites at this time.

Life-size sandstone statue from Tomb 1 of the early Celtic princely burial mound at Glauberg in Hesse, about 500 BC. B.C.
© Heinrich Stürzl (CC BY-NC-SA 3.0)

Chainmail Armour

As early as the 4th century BC, Celtic metalworkers mastered the techniques to develop their own chain mail armour. There are many Classical depictions of Celts portray them wearing mail shirts. Chain mail has been found in Late Iron Age burials from Western, Central, and especially Eastern Europe. The Romans likely first encountered chain armour in areas with Celtic presences like northern Italy.

There are a number of literary references to the Celts wearing chainmail armour:

Some of them have iron cuirasses, chain-wrought, but others are satisfied with the armour which Nature has given them and go into battle naked.

Diodorus Siculus, Library of History, Book 5, Chapter 30

Strabo described the Lusitanians, a Celtic tribe from the Iberian Peninsular.

[The Lusitanians] wear linen cuirasses; a few wear chain-wrought cuirasses and helmets with three crests, but the rest wear helmets made of sinews. The foot-soldiers wear greaves also, and each soldier has several javelins; and some also make use of spears, and the spears have bronze heads.

Strabo, Geoagraphy Book 3, Chapter 3 section 6

Appian of Alexandria (c.95-c.165) wrote about the The Seleucid War (192–188 BC) and described the Celtic tribe of the Galatians and the battle of Magnesia.

The total force of Antiochus […]  consisting of the mail-clad Galatians

Appian, The Syrian Wars 7, Chapter 6, Section 32

Chain mail may have originated among the Celts before spreading to Europe and Asia Minor as the Roman author Varro (116 – 27 BCE) mentioned in his treatise on the origin and development of the Latin language.

Lorica, quod e loris de corio crudo pectoralia faciebant; postea subcidit gallica e ferro sub id vocabulum, ex anulis ferrea tunica

Lorica, because they used to make chest-protectors from straps (lori) of untanned leather; but afterwards, the Gallic corselet of iron, an iron tunic made of rings, was included in the same word

Varro, On the Latin Language (De lingua latina libri ) Book V, 24:116

Sculpture of a chainmail-armoured, torc-wearing Gaulish warrior wielding a Celtic shield, although depicted in the Greco-Roman style, from Vacheres, France, 1st century BC
©  Fabrice Philibert-Caillat (CC BY-NC-SA 3.0)

The Warrior of Vachères (above) is a Gallo-Roman statue of a soldier. The soldier wears a Celtic torc necklace, and has a long oval shield, identifying him as a Roman Gaul. He also wears a chainmail shirt and cloak, and has a sword on his hip. It was made between the late 1st Century BC and the early 1st Century.

Two methods of manufacture were found in the mail – one alternating rows of punched-out rings with loops merely butted together (like bath-plug chains), and, the second method employed rings that were riveted together. Surviving examples of Celtic mail shirts are typically long, falling just below the waist and they would have weighed more than 14 kg (about 32 pounds). To help redistribute the weight of the iron mail, they were made with broad shoulder straps which had the benefit of adding extra protection.

Breastplate Armour

Literary references to Celtic breastplates comes from Plutarch’s account of Marcellus (d. 208 B.C.) killing Britomartus the king of the Gauls in single combat.

The king of the Gauls […] with his armour, that was adorned with gold and silver and various colours, shining like lightning. These arms seeming to Marcellus, while he viewed the enemy’s army drawn up in battalia, to be the best and fairest, and thinking them to be those he had vowed to Jupiter, he instantly ran upon the king, and pierced through his breastplate with his lance;

Plutarch, Lives of the noble Greeks and Romans, Marcus Claudius Marcellus, Section 7

Caius Marius (157-86 B.C.) fought the Celtic (or possibly Germanic) Cimbri tribe who wore breastplates

They wore helmets, made to resemble the heads and jaws of wild beasts, and other strange shapes, and heightening these with plumes of feathers, they made themselves appear taller than they were. They had breastplates of iron, and white glittering shields; and for their offensive arms, every one had two darts, and when they came hand to hand, they used large and heavy swords.

Plutarch, Lives of the noble Greeks and Romans, Caius Marius, Section 23

It is mentioned my Publius Papinius Statius in his book on poetry, ‘Silvae – Book V’ that Bolanus, governor of Britain (69-71 AD), took a breastplate from a British king to form part of a trophy.

A few surviving examples of breastplates have also been found in Hallstatt and La Tene graves, although these were very rare.

Cuirasse de Marmesse, bronze, Bronze Age, Museum of National Antiquities, Saint-Germain-en-Laye
© Calame CC BY-SA 3.0

Bronze cuirasses have been found in 8th-century BCE Hallstatt burials in Marmesse, France. These cuirasses bear some similarity to Greek and Etruscan ‘bell cuirasses’ produced in the Mediterranean during the Archaic Period (8th to 6th century BCE) and to the ‘muscle cuirass’ which developed in the 5th century BCE.

The Stična Breastplate is a double-shell breastplate made of bronze from a 6th century BCE Hallstatt warrior’s grave in modern-day Slovenia. It is decorated with appropriate human features on the chest and back.

The Warrior of Grezan (also known as Le Guerrier de Grezan) is a pre-Roman representation of a Gallic warrior. Now in the collections of the Archeology Museum of Nimes, France
The Warrior of Grezan © Andesina (CC BY-SA 4.0)

The 1st-century BCE ‘Warrior of Grezan’, one of the oldest and best examples of Celtic art depicting a warrior, may depict the figure wearing a breastplate. The three-quarter length statue is one of the better examples of pre-Roman art depicting Gallic or Celtic people. The breast plate with rectangular sun pendant and the torc is less pronounced.  The figure wears a torc necklace and pendant, in addition to a breastplate and a kind of helmet or ornate hood.

Celtic Cavalry

The Celts were renowned for their skill on horseback, and horses played an important role in Celtic culture. Elite graves dating back to the 8th Century BC are characterise by horse gear and wagons. showing the importance of horse ownership and charioteering to social status and wealth in Celtic culture and implying a growing role of cavalry in the art of war. Cavalry figures or chieftains appear on the Gundestrap cauldron (150 BC and 1 BC) and the Halstatt scabbard (Grave 995 shown above).

Spurs are shown on the Gundestrup Cauldron. Gundestrup Cauldron © Claude Valette (CC BY-SA 4.0)

It is as horsemen that Celtic warriors made their greatest impression on classical authors.

The whole race which is now called both “Gallic” and “Galatic” is war-mad […] they are better as cavalry than as infantry; and the best cavalry-force the Romans have comes from these people. 

Strabo, Geography book 4, Chapter 4, Section 2

For they [the Gauls] were most excellent fighters on horseback, and were thought to be specially superior as such …

Plutarch, Marcellus 6

Among the Gauls and Celtiberians, military horsemanship replaced chariot warfare and a more traditional style of cavalry fighting emerged. Early Celtic saddles had tall pommels to help the rider remain seated, but there were no stirrups, which were not introduced until the post-Roman period.

By this period, the elite Galllic warriors who provided the urbanarit societies with their armed retainers were almost entirely cavalry, armed with a spear, a long slashing sword protected by a helmet and mailshirt and mounted on a large horse capable of bearing the weight of the knight and his equipment. They were the equivilent of the Roman equites.

It is likely that they carried small shields, in either geometric shapes or simply round. Although the cavalry wore no clothing specific to their rank, we can assume that their higher status meant that their equipment was of better quality. Excavation at Alesia has revealed the advanced nature of Gallic horsemanship.

Two types of horse bit were found, one a simple snaffle-bit of a common form used across Europe at the time. The other, a complex curb bit, is a form invented by the Celts only a hundred years before the Battle of Alesia and would have given the rider complete command of the horse with one hand.

The Gauls were also credited with inventing spurs, although of the six spurs originally discovered at Alesia only two remain, one of iron and one of bronze. The Gauls were also notable for having developed an ingenious form of saddle, one reason for their renowned cavalry skills. Unfortunately no saddle remains have been discovered at Alesia, but contemporary examples show they had four pommels that held the rider on the horse without the need for stirrups.

Celtic Cavalry Tactics

The Celts fought as mercenaries in Greek armies, where their skill as horsemen had been particularly values. Xenophon a Greek chronicler and military commander during the Peloponnesian war (431-404 BC), described a ‘body of Celts and Iberians and about fifty cavalry’ and their use of a ‘feigned flight’ tactic against the Thebans:

But the little body of cavalry lately arrived from Dionysius spread out in a long thin line, and one at one point and one at another galloped along the front, discharging their missiles as they dashed forward, and when the enemy rushed against them, retired, and again wheeling about, showered another volley. Even while so engaged they would dismount from their horses and take breath; and if their foemen galloped up while they were so dismounted, in an instant they had leapt on their horses’ backs and were in full retreat. Or if, again, a party pursued them some distance from the main body, as soon as they turned to retire, they would press upon them, and discharging volleys of missiles, made terrible work, forcing the whole army to advance and retire, merely to keep pace with the movements of fifty horsemen.

Xenophon, Hellenica, Book 7, Section 21

Pausanias (c. 110 – c. 180 BC) describes a Celtic cavalry tactic called trimarcisia:

When the Gallic horsemen were engaged, the servants remained behind the ranks and proved useful in the following way. Should a horseman or his horse fall, the slave brought him a horse to mount; if the rider was killed, the slave mounted the horse in his master’s place; if both rider and horse were killed, there was a mounted man ready. When a rider was wounded, one slave brought back to camp the wounded man, while the other took his vacant place in the ranks.

I believe that the Gauls in adopting these methods copied the Persian regiment of the Ten Thousand, who were called the Immortals. There was, however, this difference. The Persians used to wait until the battle was over before replacing casualties, while the Gauls kept reinforcing the horsemen to their full number during the height of the action. This organization is called in their native speech trimarcisia, for I would have you know that marca is the Celtic name for a horse. [The Irish horse goddess Macha was also a goddess of war.]

Pausanias, Description of Greece 10.19.10-11

Ceasurs description of cavalry engagements during his campaigns against the Britons.

But the system of cavalry engagement is wont to produce equal danger, and indeed the same, both to those who retreat and to those who pursue. To this was added, that they [the Britons] never fought in close order, but in small parties and at great distances, and had detachments placed [in different parts], and then the one relieved the other, and the vigorous and fresh succeeded the wearied.

Caesar, Gallic Wars, Book 5, Chapter 16

Celtic Chariots

Diodorus Siculus mentions chariots in his Library of History

In their journeyings and when they go into battle the Gauls use chariots drawn by two horses, which carry the charioteer and the warrior; and when they encounter cavalry in the fighting they first hurl their javelins at the enemy and then step down from their chariots and join battle with their swords. Certain of them despise death to such a degree that they enter the perils of battle without protective armour and with no more than a girdle about their loins. They bring along to war also their free men to serve them, choosing them out from among the poor, and these attendants they use in battle as charioteers and as shield-bearers

Diodorus Siculus, Library of History, V.29.1-2; cf. Strabo, “For the purposes of war they [the Britons] use chariots for the most part, just as some of the Celti do,” IV.5.2

Noting that some tribes fight from chariots, Tacitus says that “The nobleman drives, his dependents fight in his defence” (Agricola, XII). Here, the person of higher rank is the charioteer and his client who leaps from the chariot and goes into battle.

Roman sources describe the Celts bringing both wagons and chariots into battle, and these vehicles have been found in Iron Age Celtic burials associated with warriors. Two-wheeled chariots drawn by a team of two horses are known from both archaeological and artistic evidence such as coins and burials. According to Romans, the Celts used their chariots to get into the fray and intimidate their enemies before jumping off and fighting on foot.

The absence of any reference to chariot warfare in Gaul during Caesar’s campaigns suggests that as a means of fighting it was no longer of significance. Britain and Ireland were more isolated from the changes in warfare which affected the continent, and British tribes continued to use chariots well into the Roman period.

[The Britons’] mode of fighting with their chariots is this: firstly, they drive about in all directions and throw their weapons and generally break the ranks of the enemy with the very dread of their horses and the noise of their wheels; and when they have worked themselves in between the troops of horse, leap from their chariots and engage on foot.

Caesar, Gallic Wars, book 4, Chapter 33

In Britain his chief opponent, Cassivellaunus, was able to muster 4,000 chariots, which, if used
together, must have been a formidable sight.