Origins: Sarmatians, Alans, Parthians and Persians:
The draco Standard was originally developed by the cavalry peoples of the steppes, such as the Sarmatians and the Alans, but also by the Parthians and the Sassanid Persians. It may have been used primarily to determine the wind-direction for the horse archers. Arrian described it as a long sleeve, 'made by sewing pieces of dyed material together'. This sleeve/tube hung limp when the rider was at rest, but on the move it flew like a serpent and whistled in the wind. The hollow head, in the form of a toothed dragon, was formed from metal and the wind passing through it would extend the cloth tube tail attached to the neck of the head. The draco was also used by the Dacians (or their allies) and no less than 20 of these are shown on Trajan's Column. Other sources mention Parthian and Sassanid Persian dracos.
Not all such standards had dragon heads. The one below on the left from Trajan's Column shows the tubular tail with streamers attached. The head looks more like a dog (with ears) than a dragon. The one beside it has a much more serpentine head, and has scalloped rings attached to the tail. Other standards had no heads at all, just the fabric tube, while some had heads looking like wolves or even fishes. These had protruding ears and fins. The images below show part of the Arch of Galerius with several dracos.
The Roman draco
The Draco was adopted first into the Roman cavalry during the 2nd century AD, possibly with the introduction of Sarmatian cavalry into the Roman army. Arrian, who was writing c. 137 AD, described it as a Scythian (he most probably meant Sarmatian) invention which was adopted by Roman cavalry. The Romans first began to use the draco in cavalry games, the so-called 'Hippica Gymnasia'. These were described by Arrian as glamorised versions of training exercises, performed in decorated armour. It is possible that the draco was introduced just because it was 'outlandish', foreign and glamourous. Points in the game were scored for strikes on the tail piece of the dracos carried by a team acting as 'targets', from dummy javelins thrown by another team of riders. Arrian recommended that the standard be colorful, adding to to the spectacle of cavalry parades. One should be given to each unit to maintain order in both displays and battle. The Roman cavalry adopted the draco probably during or after the Dacian wars, in which the equipment of the Roman cavalry was altere to withstand the charged of the lance-armed cavalry. These equipment changes included the adoption of the fully-armed cavalry (alae cataphractiorum) and the long lance. It would be logical to assume that this was the time when also the draco standard was introduced.
The choice for the dragon/serpent as model is not so easy to explain, because the steppe cultures used other animal's heads and continued to do so. However, it has been assumed that it was because of the Thracian dominance in Roman cavalry that the latter adopted the serpent shape. These Thracian horsemen had a deity which resembled a 'flying' serpent with scales, teeth and an upstanding crest, which may well have been a draco or something similar.
It is not documented when exactly the draco was adopted as a normal standard for all troop types. However, sources mention the draco being used with the infantry. The Historia Augusta mentions that the mother of Severus (193-211 AD) dreamt of a puple snake before his birth, something very alike what we later hear of the Imperial standard[3]. But since this source was probably compiled later, we can't be sure this has any bearing on a dating. We are on more solid ground with the entry of the reign of Gallienus (253-268 AD), when legionary troops are said to have paraded with a dracon amongst the standards of the legions[4] and the troops of Aurelianus (270-5 AD) also had draconarii amongst the standard-bearers[5]. This may lead us to conclude that the infantry began using dracos during the late 3rd c. On the Arch of Galerius, which was built before 311 AD to commemorate Galerius' war against Persia in 290 AD, several dracos can be seen to his left and right, carried by infantry as well as cavalry (see the image above, 2nd from right).
We have no good idea about the general appearance of the draco. Some draco heads may have looked like a draco, but some seem to look more like wolves or dogs, or even of an ass (..).
Also, we can't be sure of the lenght of the windsock, or the actual length of the pole on which it was carried.
However, the coins of the Emperor Trajan Decius (AD 249-251) give us some idea as to tall the latter was. If not a representation of a boar-headed trumpet (carnycus), it does not seem to have been taller than a man. In my opinion though, the Emperor would rather be shown with an standard.
The draco head was most probably constructed by first carving a wooden original, then beating a copper alloy sheet around it. This draco head was made of two halves, the bottom jaw being riveted against the top half. Adding a windsock may be a problem, because we have no clear idea how long it would be. However, trial and error will get you there, with of course different lengths and materials possible. I'd go for silk, which may be expensive, but it is light and gets the best result. Possibly, added hoops might keep the tail 'inflated', which can also be used to attach strips of cloth to create the 'streaming' effect of the flying beast described by Arrian (Ars. Tact. 35.3-4). The images below show a 2nd-3rd C. funeral stele from Chester, probably showing a Sarmatian draconarius.
The Niederbieber draco
The Roman draco developed into a real dragon, without ears but with scales and a crest. The only fully preserved draco was found in the Limes fortress of Niederbieber in Germany, which dates to the 3rd century. This copper alloy object was discovered near the SW edge of the vicus (civilian settlement) outside the fort. It can best be described as a scaled monster's head, measuring 30x12x12 cm, and with some probability is the head of a cohort's draco.
It is formed by the joining of two embossed sheets, the gilded upper one overlapping the lower tinned one, both attached by 5 rivets on each side. At the base of the neck the sheets form a circular flange, riveted together by 2 more rivets. Overlapping scales cover the head and neck, while a series of ridges covers the upper jaw from the nostrils to the eyes, which face sideways. The open mouth shows triangular teeth, but no fangs or canines. A crenellated crest is attached to the top of the head.
Two holes of similar size are pierced through both the throat and the skull behind the crest. No doubt a staff or the shaft of a spear would pass through here. Two axial slits, 2 cm long, pierce the botom of the lower jaw, probably to attach a lost mechanism that would have produced the hissing effect.
The draco in the Late Roman army
The late 4th c. author Vegetius also mentions the draco as a common standard. He seems to have been confused about the difference between the old standards and the new dragons though, as he wrote that apparently standard- and draco-bearers differ[6], but also that the standardbearers 'are now named dragonbearers[7], that both are present in a camp[8], but also that each cohort has a draco[9]. if correct it would mean the first overall standard for the cohort (where before none had existed between the legionary aquila and the signa of the centuries). the draco may have foreshadowed the later common practise in the 3rd century to permanently detach cohortes from their parent legions.
By 357 AD, the Emperors Constantius and Julian (who was crowned by a draconarius[10]) had personal dracos sewn from a purple material. Ammianus Marcellinus writes of flags as well as draco being purple[11] and mentions them making a hissing sound in the wind[12]. The Emperor's personal draco standards made them identifyable in the heat of battle and may therefore have been mainly a tactital instrument rather than a personal adornment. Julian's draco at the battle of Argentorate (357) was important in his attempt to regain control of the battle[13]. The early 5th/c. author Zosimus also mentions Julian being extremely cross when one was lost to the enemy during the Persian campaign[14] .
By the fifth century, as may be deduced from inscriptions from Perge and Prusias/Üskübü, Turkey, as well as a poem by Prudentius, there was a rank called magister draconum. This officer was the superior of the draconarii in a unit, ranking immediately below the tribune. However, we don't know if he directed the draconarii in battle, or may just have been the head of the standard bearers' club or scholae. The magister draconum probably replaced the optio signiferorum, whose function unfortunately is equally vague. Other ranks are less clear: from Cagliari/Sardinia we know an optio draconarius, while the bearcus draconarius seems to have been an unusually high-ranking draconarius.
Prudentius also tells us that Late Roman draconarii wore golden torcs as reward for their valor in battle. However, we learn from Ammianus that the torc may have been a badge of office, so possibly standard bearers were selected from those who had earlier received such torcs, marking them for an elite.
The East Roman or 'Byzantine' draconarius
Around the mid-6th century, the historian Johannes Lydos mentioned the draconarius (drakonarioi-drakontophoroi) in a list of ranks and functions[15]. Justinian also mentioned a corps of 10 draconarii in his edict of 534, issued to Belisarius in North Africa[16]. The military manual called the Strategikon of the emperor Maurikios (582-602 AD) shows that draconarii were probably still around in the early 7th. century. However, it is not clear whether the draconarius mentioned there [17] was already anachronistic or if he still had a proper military function - there was a scholae draconariorum, a non-military office staff of 10 clercs attached to a civilian praefectus praetorio. After the 6th century, the draconarius disappeared from the Byzantine army.
After the Romans
Dracos continued in use in the Caucasus and Georgia, while in the West the Franks under Charlemagne may have adopted them again. This may show continuity, or else Charlemagne's attempts to eminate the Roman Army. We have a miniature from the late 9th-c. Psalterium Aureum (MS St. Gall. Stift-Bib. 22, fol. 140, illustrating Psalm 59), which shows a draco in a formation of heavy cavalry.
We also see it used at the battle of Hastings in 1066 AD, where it is carried by Harold Godwinson's retainer at the moment of his death.
The next image is from a 14th-century manuscript of L'Histoire de Merlin by Robert de Boron, now in the Bibliotheque Nationale in Paris. It shows King Arthur in combat, brandishing what can only be a Medieval representation of a Late Roman draco. This is not supposed to reflect 14th-c. battle standards, but rather a fanciful idea of ancient use.
The last image shows the flag of modern Wales, in Welsh called Y Draig Goch (The Red Dragon). This red dragon, as the tale goes, would go back to the myth of the red and white dragons fighting on Vortigern's fort at Dinas Emrys in Gwynedd, Wales. These dragons, though, are thought by some to represent the draco of the Late Roman army.
The Dragon of Wessex, like the Red Dragon of Wales, may indeed represent some form of continuity. However, it could also show Francish influence in England and Wales during the early Middle Ages, as well as an antiquity-related Romanticism which has nothing to do with reality any more.