Battle of Strasbourg

Infobox Military Conflict
conflict=Battle of Strasbourg
partof=the Roman-Alamanni conflict


caption=Coin showing (obverse) head of Julian (emperor 361-3) with diadem and (reverse) soldier bearing standard holding kneeling captive by the hair and legend VIRTVS EXERCITVS ROMANORVM ("Courage of the Roman army"). Gold "solidus". Sirmium mint
date=357
place=Strasbourg
result=Roman victory
combatant1=Roman Empire
combatant2=Alamanni
commander1=Julian (deputy emperor)
Severus
("magister equitum")
commander2=Chnodomar (high king)
Serapio (2nd-in-command)
strength1=13,000Ammianus XVI.12.2]
(inc. est. 3,000 cavalry)Elton (1996) 106]
strength2=ca. 35,000Ammianus XVI.12.26]
casualties1=243 deadAmmianus XVI.12.63]
casualties2=6,000 dead in the field. Unknown but large
number drowned
crossing river Rhine

The Battle of Strasbourg, also known as the Battle of Argentoratum, was fought in 357 between the Late Roman army under the "Caesar" (deputy emperor) Julian and the Alamanni tribal confederation led by the joint paramount king Chnodomar. The battle took place near Strasbourg (Alsace, France), called "Argentoratum" in Ammianus Marcellinus' account, but officially called "Argentorate" by the Romans. ["Tabula Peutingeriana Section 2"]

Although outnumbered three to one, Julian's army won a complete victory after a hard-fought struggle. With negligible casualties of their own, the Romans drove the Alamanni beyond the river Rhine inflcting heavy losses. Julian's force, the imperial escort army of Gaul, was small but high-quality. The battle was won by the skill of the Roman infantry, with the cavalry performing poorly.

The battle was the climax of Julian's campaigns in 355-7 to evict barbarian marauders from Gaul and to restore the Roman defensive line of forts along the river Rhine, which had been largely destroyed during the Roman civil war of 350-3. In the years following his victory at Strasbourg, Julian was able to repair and garrison the Rhine forts and impose tributary status on the Germanic tribes beyond the border.

Sources

By far the most detailed and reliable source for the battle, and Julian's Gallic campaign (355-60) generally, is the "Res Gestae" (Histories) of Ammianus Marcellinus, a contemporary historian. Ammianus was a Greek career soldier who joined the army before 350 and served until at least 363. [Ammianus XXXI.16.9] Enlisted as a "protector" (cadet senior officer), he served as a staff officer under "magister equitum" Ursicinus and then under Julian himself in the latter's Persian campaign. He had experience of the Gallic front as he was involved in the suppression of the revolt of Silvanus, the "magister equitum" in Gaul (355). [Ammianus XV.5.22] His personal experience in the high command of the military of the time makes him a reliable and valuable source. However, he is revealed as a great admirer of Julian by his narrative, which occasionally descends to the level of eulogy. This results in a tendency to excessive praise of Julian's performance and to hostility to his enemies.

The late 5th century Byzantine chronicler Zosimus's "Nova Historia" deals with the battle, and Julian's Gallic campaign in a summary fashion and adds little to Ammianus' account. But Zosimus is useful because his account of the revolt of Magnentius (350-3) survives, unlike Ammianus', which is contained in the 13 lost books of his history.

The contemporary rhetorician Libanius delivered "Julian's funeral oration" (363). This contains some details which are missing in Ammianus, which he presumably learnt from members of Julian's entourage. But because his is a eulogy, not a historical narrative, the reliability of his account of Julian's campaign is doubtful, and Ammianus' version is to be preferred where there is a contradiction.

The Alamanni

During the third century, the small and fragmented tribes of "Germania Libera" ("free Germany" i.e. Germany outside the empire) apparently coalesced into large, loose confederations: the Franks (NW Germany), Alamanni (SW Germany) and Burgundians (Central Germany). [Goldsworthy (2000) 178] Although riven by internal feuding, these confederations could mobilise large forces and may have presented a greater threat to the empire than previously.

The Alamanni were a loose confederation of Germanic tribes who, originally from the Main valley of central Germany, had colonised the "Agri Decumates" (roughly the modern state of Baden-Württemberg in SW Germany) after it was evacuated by the Romans in the mid-3rd century after being part of the Roman province of Germania Superior for over 150 years. The Alamanni established a series of territorially defined "pagi" (cantons) on the east bank of the Rhine. The exact number and extent of these "pagi" is unclear and probably changed over time.

"Pagi", usually pairs of "pagi" combined, formed kingdoms ("regna") which, it is generally believed, were permanent and hereditary. Ammianus describes Alamanni rulers with various terms: "reges excelsiores ante alios" ("paramount kings"), "reges proximi" ("neighbouring kings"), "reguli" ("petty kings") and "regales" ("princes"). This may be a formal hierarchy, or they may be vague, overlapping terms, or a combination of both. [Drinkwater (2007) 118, 120] In 357, there appears to have been two paramount kings (Chnodomar and Westralp) who probably acted as presidents of the confederation and 7 - 9 other kings ("reges"). Their territories were small and mostly strung along the Rhine (although some were clearly in the interior). [Drinkwater (2007) 223 (map)] It is possible that the "reguli" were the rulers of the two "pagi" in each kingdom. Underneath the royal class were the nobles (called "optimates" by the Romans) and warriors (called "armati" by the Romans). The warriors consisted of professional warbands and levies of free men. [Speidel (2004)] Each nobleman could raise an average of ca. 50 warriors. [Drinkwater (2007) 120]

The total Germanic population of "Alamannia" at this time has been estimated at a tiny 120,000 - 150,000. This compares with ca. 10 million in Gaul. [Drinkwater (2007) 143; Elton (1996) 73] Alamanni society was a violent warrior-society based on feuding clans. [Drinkwater (2007) 121] This bred good warriors ("armati"). The maximum number of warriors the Alamanni could raise appears to have been 30-40,000.Elton (1996) 73]

Invasion of Gaul

In January 350, the Roman empire was ruled by two sons of Constantine I the Great, the "Augusti" (joint emperors) Constans, who ruled the West, and Constantius II in the East. But in that month, Constans was overthrown and killed by the usurper Magnentius, a "laetus" from Gaul who was "comes" (commander) of the elite brigade in Constans' "comitatus" (imperial escort army).Zosimus II.58] In the East, Constantius had been engaged in a lengthy war against the Persians under Shah Shapur II (337-50). But he immediately concluded a truce in order to deal with Magnentius. He led his own "comitatus" to Illyricum where he assumed command of the local "comitatus" also, bringing his combined strike force to ca. 60,000. [Zosimus II.59] Magnentius gathered an army consisting of the Gaul "comitatus" and probably some Frankish and Saxon "foederati" (allies) and marched into Illyricum to attack Constantius. [Elton (1996) 231] (For explanation of the term "comitatus", see Late Roman army).

The Franks and Alamanni on the Rhine frontier now seized on the opportunity presented by the absence of the best Roman forces in the civil war to overrun much of eastern Gaul and Raetia. [Ammianus XV.5.2] Libanius claims that they were incited to do so by letters from Constantius, in order to create a diversion in Magnentius' rear. [Libanius 133] The barbarians captured many of the Roman forts along the Rhine, destroyed their fortifications and established permanent camps on the West bank of the river, which they used as bases to pillage Gaul during the four years that the civil war lasted (350-3). In excess of 20,000 Roman civilians are believed to have been abducted from Gaul and enslaved. [Julian "Epistulae ad Athenienses" 280] Libanius claims that the latter were forced to farm the Alamanni's fields. [Libanius 18.34] In turn, this would have reinforced Alamanni raiding in Gaul by freeing many from the harvest cycle.

Meanwhile, most of the Gaul "comitatus" and perhaps half the Illyricum force were wiped out in the civil war. At the Battle of Mursa in Pannonia (351), one of the bloodiest in Roman history, Magnentius lost an estimated 24,000 men (perhaps two-thirds of his army). Constantius' army, although victorious, suffered even greater casualties (ca. 30,000). [Britannica Online "Battle of Mursa"] . A final encounter at the Battle of Mons Seleucus in the Alps saw further casualties. Such massive losses of first-grade troops could not quickly or easily be replaced. Manpower was further stretched by the demands of a renewed Persian threat in the East. In addition to his own large "comitatus", now based in Milan, Constantius reconstituted a "comitatus" in the East and a substantial force in Illyricum. [Jones (1964)] He thus had few troops to spare for Gaul.

Constantius succeeded in driving the Alamanni out of Raetia (354), and binding the kings of southern Alamannia, Wadomar and Gundomad, with a treaty of alliance. [Ammianus XV.4] But the following year (355), the brief usurpation of Silvanus, the "magister equitum" in Gaul, convinced a shaken Constantius that he needed a member of his own "Flavii" (Constantinian) clan to take charge in the West. He thus appointed his cousin Julian as "Caesar" (deputy emperor) for the West and gave him the command of forces in Gaul, including a much-reduced "comitatus". [Ammianus XV.8.1] . The appointment was widely seen as unsuitable as Julian, who was just 23 years old, had no military experience and had until that moment spent his time studying philosophy at Athens. [Libanius 132] But Constantius had little choice: Julian was his sole surviving male relative as a result of the emperor's own paranoid purges of his family members. In the event, Julian surprised everyone by proving a highly effective military leader.

The task confronting Julian as he took up his post was daunting. The civil war had left Gaul in a chaotic state. [Ammianus XV.8.1] The defensive line of the Rhine had largely collapsed. According to Ammianus, the Franks had taken "Colonia Agrippina" (Cologne) by storm and razed it to the ground. "Moguntiacum" (Mainz), "Borbetomagus" (Worms), "Nemetae Vangionum" (Speyer), "Tabernae" (Saverne), "Saliso" (Brumat) and "Argentorate" (Strasbourg) were all in German hands. Only three strongpoints on the Rhine remained in Roman hands: a single tower near Cologne and two forts, at "Rigodunum" (Remagen) and "Confluentes" (Koblenz). [Ammianus XVI.2.12 and XVI.3.1] Large barbarian bands were roaming and pillaging eastern Gaul at will, reaching as far as the river Seine. [Ammianus XVI.2.1-7] So many and so large were the marauding enemy bands that Silvanus was considered a brave man for having led 8,000 men along a wooded highway in the heart of Gaul because of the risk of ambush. [Ammianus XVI.2.3-4] At the same time, the forces at Julian's disposal were very limited. Julian's "comitatus" numbered 13,000, only a third of the army Magnentius fought with at Mursa. Further, the "limitanei" (border protection forces) along the Rhine must have been decimated by the fall of most of their forts to the Germans, while those units that survived intact had retreated from the frontier to garrison Gaul's cities. Cynics at court whispered that Julian had been given an impossible mission to rid Constantius of a potential rival for the throne. [Ammianus XVI.11.13]

Prelude

Julian spent the winter of 355/6 with his army at "Vienna" (Vienne). When the 356 campaigning season began, he risked ambush by taking a heavily wooded route with some cavalry to relieve "Augustodunum" (Autun), which was being assailed by a large barbarian force. The surprised German attackers took flight. Julian then assembled his whole army at "Remi" (Rheims), under his deputy, the "magister equitum" Marcellus. From there he set out to retake the critical lower Rhine city of Cologne, and its fortress across the river at Divitia (Deutz), built by Constantine the Great. Beating off a major German ambush along the way, his forces recaptured Cologne. Julian then concluded a peace treaty with the Franks. [Ammianus XVI.3.2] This had the important effect of cutting the opposition in half and allowing Julian to focus his resources on dealing with the Alamanni.

For the winter of 356/7, he chose "Senones" (Sens) near Paris as his base, but quartered some troops in other towns to spread the burden. A large band of Alamanni heard of his reduced escort, however, and besieged him at Sens. Julian's forces were able to hold out until, after a month, the Germans withdrew. He was so outnumbered by the enemy, however, that he was unable to sally forth and offer battle. The same factor may have prevented Marcellus at nearby Rheims from attempting to relieve him, a failure criticised by Ammianus. [Ammianus XVI.4] In any event, Marcellus was dismissed as "magister equitum" by Constantius and replaced by Severus, a distinguished officer who was more compatible with Julian. [Ammianus XVI.7.1]

For the 357 campaign season, a plan was laid down at Constantius' headquarters in "Mediolanum" (Milan) to trap the Alamanni in eastern Gaul in a pincer movement. Julian would advance eastward from Rheims, while the major part of Constantius' "comitatus" in Italy (25,000 strong) was despatched under "magister peditum" Barbatio to "Augusta Rauracorum" (Augst) in Raetia. The Alamanni bands would be cornered and destroyed in the southern part of "Germania I" province (Alsace). [Ammianus XVI.11.1-2]

But the main body of Alamanni, instead of trying to escape the Roman pincer movement by retreating across the Rhine, showed their contempt for the Roman army by invading and ravaging the Rhone valley, even trying to take the major city of "Lugdunum" (Lyon) by assault. The attack was repulsed as the walls of the city proved too strong and the garrison, presumably "limitanei" troops, too valorous. [Ammianus XVI.11.4] But although they had taken vast amounts of booty, the Alamanni were now trapped in the interior of Gaul with their way back to the Rhine barred by the Roman armies.

But part of the German force escaped. In Julian's sector, they were duly intercepted and destroyed by squadrons of cavalry sent by the Caesar to lie in ambush on three highways. But in Barbatio's sector, the Germans were allowed to pass unmolested by Barbatio's "magister equitum" Cella, who refused to authorise the cavalry commanders Valentinian (later emperor Valentinian I ruled 364-5) and Bainobaudes to deploy on a highway that they were sure the enemy would use. [Ammianus XVI.11.6] Nevertheless, Julian pursued them vigorously, surprising one group by crossing the Rhine, which had become passable at some points due to summer drought and slaughtering many. The Germans beyond the Rhine offered Julian no resistance, but took refuge in forests and swamps, allowing Julian to burn their villages and crops unhindered. They eventually sued for peace. [Ammianus XVI.11.8-9, 12.5] Julian now turned his attention to rebuilding the fortress at Saverne, which had been destroyed by the Alamanni. Saverne lay astride the "Mettis" (Metz) - Strasbourg Roman highway, at the mouth of the main entry route through the Vosges mountains into northern Alsace. Its strategic location, and commanding heights overlooking the Rhine valley, explains why it was a priority for Julian. While this work was proceeding, Barbatio's army was attacked just outside Severus' camp by a large barbarian force. Instead of fighting, Barbatio's men fled and were pursued as far Augst. At this point, Barbatio, whose cooperation with Julian had been grudging at best, withdrew his army from Gaul altogether without Julian's permission, sending his forces into winter quarters in Italy, even though the Alamanni were far from ejected from Alsace or beaten. [Ammianus XVI.11.14-15] This left Julian exposed, with only 13,000 men.

At this time, the Alamanni confederation appears to have been under the presidency of two paramount kings, Chnodomar and Westralp. [Ammianus XVI.12.1] But Chnodomar was the driving force. A man of prodigious stature, strength and energy, he was nicknamed "Gigas" ("the Giant") by the Romans. [Libanius 143] He was a formidable sight in his "flashing" helmet (probably gold-leafed) and full parade armour. He is described by Ammianus as the "evil mastermind" behind the invasion of Gaul. [Ammianus XVI.12.24]

Chnodomar could not ignore Julian's fortification of Saverne, as it threatened his control of Alsace and blocked his main access route into the interior of Gaul. He had come to see this region as Alamanni territory by right of conquest after occupying it for several years. He claimed to possess letters from Constantius granting the Alamanni the right to occupy those lands. [Libanius 139] Chnodomar had been surprised and dismayed by Julian's successful campaigns of 355-7. But he was encouraged by his success against Barbatio and the intelligence brought to him by a deserter that Barbatio's withdrawal had left the "Caesar" with a relatively small force. Having defeated two Roman "magistri equitum" (Decentius and Barbatio) in the field, Chnodomar had lost the barbarians' traditional fear of pitched battles with the Romans. [Ammianus XVI.12.5]

The Alamanni high kings now ordered a mass mobilisation of all the confederation's member tribes. They gathered their disparate bands. In addition, they received the timely support of the two Alamanni tribes near Raetia that had been pacified by Constantius in 355. Their leaders were overthrown by an anti-Roman coup by their "optimates". Gundomad was slain and Wadomar forced to break his treaty and join Chnodomar. [Ammianus XVI.12.17] Finally, they summoned the assistance of non-Alamanni tribes, partly for services rendered in the past, partly for payment. At Strasbourg on the Rhine (about 32km SE of Saverne), they gathered a combined force of some 35,000 men. Their aim was to bring Julian to battle and crush him by sheer weight of numbers. They provoked Julian by sending him an insolent ultimatum to evacuate Alsace immediately. [Ammianus XVI.12.3]

Julian was now faced with a finely-balanced judgement call. The safer option was to ignore Chnodomar's challenge and to keep his forces in their fortified bases and request and await reinforcements, if necessary until the following year's campaign season. But the performance of Barbatio and the imperial "comitatus" in the recent campaign cast doubt on whether such reinforcements would be supplied and on their value if they were. Such a course would also expose Gaul to a massive Germanic invasion just when the harvest was due. Alternatively, he could fight Chnodomar alone. This offered the prospect of a decisive victory, since the Alamanni forces were now, unusually, concentrated and not divided into several bands. This argument was strongly made by Florentius, the "praefectus praetorio Galliarum" (governor-general of Gaul), who had the crucial job of ensuring the army's supplies. [Ammianus XVI.12.14] The Romans almost always won pitched battles with barbarians, because of their superior equipment, organisation and training. [Elton (1996) 80] But in this case it was clearly a high-risk option because of the Germans' massive superiority in numbers. Nevertheless Julian, who was renowned for his fearlessness, decided to offer Chnodomar battle alone.

The adversaries compared

According to Ammianus, a deserter informed Chnodomar that Julian had 13,000 men with him at Saverne. But this leaves open the possibility that he may have summoned more to join him for the battle. It is possible that Severus' division was additional, as it is stated that during the rout of Barbatio, his men occupied a separate camp from the main force. [Ammianus XVI.11.14] Libanius implies that Julian had 15,000 men under his command. [Libanius 138] If this was true, the additional 2,000 may have been Severus' division. Also, Julian may have been able to call on some "limitanei" units to assist him. Zosimus states that on arrival in Gaul, Julian set about a major recruitment effort. [Zosimus III.67] This was presumably in order not only to fill vacancies in his "comitatus" units, but mainly to reconstitute "limitanei" regiments that had largely dissolved during the years of anarchy.

At the same time, it has been suggested that Ammianus' estimate of 35,000 Alamanni is exaggerated and that in reality they may have been only ca. 15,000, much the same as the Romans. [Drinkwater (2007) 239] But this calculation is based on speculative assumptions including that the average size of Alamanni raiding groups (800 men) represented the maximum manpower of a "pagus". The 35,000 figure is consistent with two other figures for Alamannic armies in Ammianus: an army of 40,000 in 378; and in 366 an army divided in three, with one division 10,000 strong. In the absence of hard evidence to the contrary, it is best to accept Ammianus' figure.

Julian's force, although relatively small, was of high quality, containing some of the best regiments in the Late Roman army, with an awesome combat reputation. [Ammianus XVI.12.43] All were palatini (top-grade regiments). A substantial proportion of his troops were of barbarian, mainly Germanic, origin. An analysis of known names of officers and men in the "auxilia palatina" regiments suggests that anywhere between a third and a half of the effectives were barbarian (compared to ca. 25% in the late army as a whole). [Elton (1996) 148, 151] Of these, many would probably have been Alamanni. But the history of Julian's Gallic campaign shows that his barbarian troops were fiercely loyal and reliable. It is true that there were a few isolated cases of Germanic deserters who defected to the enemy, mostly for personal reasons, not out of ethnic solidarity. [Ammianus XVI.12.2] The only recorded instance of the latter was an officer who allegedly alerted members of his own tribe that Julian was planning a campaign against them. But in the vast majority of cases, it is clear that regimental loyalties prevailed over ethnic ones. This is evidenced by the fierce alacrity of Julian's troops to engage with the enemy and the determination with which they fought the battle (3 of the 4 "tribuni" killed at Strasbourg had barbarian names). [Ammianus XVI.12.63]

Chnodomar's men were of much less even quality. His best warriors were the professional retinues of the "regales" (royal class, called "ringgivers" by the Germans), organized in warbands. These consisted mostly of berserkers and long-haired swordfighters. They were well-equipped, as behove their masters' status. They wore little armour on purpose to ensure speed and, for the berserkers, power in doublehanded swordfighting (they wore their shield on their backs). [Speidel (2004) 66, 71, 176, 185] The majority of his men, however, were temporary levies of little training, like all contemporary Germanic forces relying on light equipment and speed.

Roman military equipment was mass-produced in state-run "fabricae" ("factories") which brought together advanced forging technology and skilled artisans. [Elton (1996) 116] Roman weapons were mostly made of internally produced steel such as "chalybs Noricus" which, although of far lower quality than the best contemporary steel made in Central Asia and China, was much superior to unhardened iron. [Ovid "Metamorphoses" ] In contrast, forging technology, capacity and personnel were more limited in "Germania libera", although there is evidence that production and standardization of equipment had greatly improved since the time of the Roman Principate. Steel-making was also known in "Germania libera" (spathae and rapier-like swords out of flexible steel were in use). [Raddatz (1967) 9-10] But Alamanni production of sophisticated forge-products such as metal armour, helmets and swords was on a much smaller scale than the Romans'. [Elton (1996) 69] Simple weapons such as axes and knives seem often to have been made of unhardened iron.

For personal protection, most Roman troops wore metal body armour (usually in the form a chain mail cuirass) and helmets, in addition to shields. [Elton (1996) 107] In contrast, among the Alamanni, metal armour and helmets were probably owned by members of the social elite only. Most Alamanni foot soldiers had only shields and no metal armour or helmets. [Elton (1996) 69]

For hand weapons, most Roman foot carried a spear ("hasta"), a sword ("spatha") and a dagger ("pumnal"). [Elton (1996) 107] Among the Alamanni, spears were the universal weapon, swords were probably less common. [Elton (1996) 67] Nobles ("optimates") and the professional warrior-retainers of "ringgivers" certainly had them. [Speidel (2004) 175] For the lower ranks the position is not certain. Ammianus' report on the battle implies that many in the Alamanni ranks carried swords. [Ammianus XVI.12.44 and 46] Those that did not were armed with or "saxes" (long pointed knives) and axes.

For short-range missile (throwing) weapons, a Roman infantryman would probably either a long throwing-spear or two or three short javelins ("lanceae") and half a dozen "plumbatae" (weighted darts) with an effective range of ca. 30m. [Goldsworthy (2005) 205] Ammianus talks of a variety of missiles being thrown by the Alamanni in the battle: "spicula" (a kind of long "pilum"-type javelin, also known as an angon), "verruta missilia" (short throwing-spears) and "ferratae arundines" (probably darts and franciscas: throwing-axes). [Ammianus XVI.12.46] [Elton (1996) 65] Overall, there appears little difference in the throwing-missile capability of the contenders. Ammianus indicates that the Roman infantry ranks were obliged to hold their shields above their heads for much of the time due to the volume of missiles raining down on them. [Ammianus XVI.12.44]

One aspect of the line-up that Ammianus is silent about is long-range missile capability (archery). But it is highly likely that there were archers on both sides. On the Roman side, Ammianus attests one "vexillatio" of "equites sagittarii" (mounted archers) at Strasbourg. [Ammianus XVI.12.7] It is also likely that at least one regiment of foot archers took part, probably an "auxilium" of "sagittarii" (archers). There were thus probably ca. 1,000 archers in dedicated units on the Roman side. In addition, a number of ordinary infantry units probably contained archers. [Goldsworthy (2005) 205] The standard Roman bow was the recurved composite bow of Central Asian design, a sophisticated, compact and powerful weapon. [Goldsworthy (1995) 137] Bows of various types were also used by the Alamanni. Most would have been inferior to the recurved bow. But the most common type, the yew longbow, was a very powerful weapon. As tall as a man, it could launch arrows with enough power to pierce armour. It is believed that such bows became widespread in "Germania libera" in the 4th century. [Raddatz (1967) ] The longbow's long range made it suitable for shooting volleys from the rear over the heads of one's own infantry lines, but its size made it impractical to use in mêlées, or on horseback (for which the recurved bow was ideal). The archery capability of the Rhine Germans has traditionally been seen as negligible, due to the 6th century writer Agathias's comment that the Franks did not know how to use bows. [Elton (1996) 64] But this is contradicted by the archaeological record and by Ammianus himself. [Ammianus XXVII.1.3; XXXI.10.8] Overall, the 4th century Roman soldier's equipment was superior to his enemy's, though probably not as much as in earlier centuries. [Mattingly (2006) 248]

The Roman cavalry was also clearly superior to Chnodomar's in armour and training, but not numbers and speed. It is estimated at ca. 3,000. [Elton (1996) 106] The Romans not only deployed light cavalry like the Germans', but also semi-armoured (with mail cuirass) and heavily-armoured cavalry. The latter were called "cataphracti" or "clibanarii" (these terms were probably interchangeable and did not indicate any significant difference in equipment). These were covered neck to toe in scale and/or lamellar articulated armour and were armed with a "contus", a long heavy lance, as well as a sword. Since Ammianus implies at least two "cataphracti" regiments, they probably constituted about a third of the Roman cavalry (1,000). The size of Chnodomar's cavalry is unknown, but was probably a small proportion of the total, as the Alamanni's heavily forested land was not suited to large-scale horse breeding. [Elton (1996) 58] Most of the Alamanni horsemen were noblemen and their retainers, as only they could afford to keep a warhorse. They are unlikely to have exceeded a fifth of the force total (7,000) and were probably considerably less. [Elton (1996) 58] Even so, they may have outnumbered the Romans significantly. Being of a wealthier class, most of Chnodomar's horsemen probably had swords, but lacked metal armour. [Elton (1996) 68] Their lack of armour would have made the Germans vulnerable to the Romans in a mêlée, especially to the "cataphracti". It is possible some of the Alamanni horse wore captured mail shirts.

Regarding training, the Roman troops were career professionals, constantly drilled in formation manoeuvres and combat techniques. [Elton (1996) 235] [Goldsworthy (2005) 93] Their most important advantage in a pitched battle was formation drill: the ability to hold one's position in a unit at regular intervals, and to replace fallen comrades, so that a unit maintains its shape and coherence as it moves or engages. On the Alamanni side, there is little evidence of formation manoeuvres. The professional retainers of the "regales" may have had some capacity for this: Ammianus' account mentions a "globus" (mass) of the best warriors coming together in the thick of the battle and breaking through the Roman line. [Ammianus XVI.12.49] In addition several would likely have served in the Roman army in the past. [Drinkwater (2007) "Service"] But the majority of Chnodomar's men consisted of temporary levies, whose training was very limited. According to Ammianus, they had to rely on a crude frontal charge to break through by weight of numbers, and proved no match for the Romans in the final phase of the battle, a prolonged struggle of attrition at close-quarters. [Ammianus XVI.12.43; 49-51]

To counter the clear tactical inferiority of his troops, Chnodomar would have relied on terrain and stratagems. [Elton 1996 ] At Strasbourg, his right flank was protected by shrubland broken up by natural dips, effectively impassable to cavalry.Ammianus XVI.12.27] Here Chnodomar set up an ambush by hiding warriors in the dips. These presumably were directed to wait for a good opportunity to surprise the Roman left wing. To deal with the "cataphracti" threat on his left, he devised a stratagem. He interspersed lightly-armed infantry among his cavalry. The idea was that in a mêlée, the foot soldiers would bring down the "cataphracti" by crawling along the ground and stabbing their horses in their underbellies, which were unprotected. The dismounted riders, weighed down by their armour, could then be easily despatched. [Ammianus XVI.12.22]

For Julian, the central tactical challenge was how to respond to the Germans' much greater numbers. Their sheer weight made it likely that they would succeed in breaking through the Roman line at one or more points. Julian's solution was to draw up his troops in two lines, front and rear, widely spaced apart. [Ammianus XVI.12.20 and 49] The rear line troops could succour those of the front line at points where the latter were in difficulty. The rear line would also act as a reserve line of defence should the front line collapse entirely. In addition, Julian probably posted a small separate division on the left flank, facing the woods beyond the highway, under his "magister equitum" Severus. [Goldsworthy (2000) fig. on p.176] This was presumably to guard against a possible German sally from that quarter, although Ammianus implies that Severus had orders to advance into the woods. For offence, Julian was relying on his cavalry to rout the enemy cavalry and the encircle their infantry from the rear.

Battle

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http://i85.photobucket.com/albums/k75/dogpng1/KOLR/horse7.jpgReenactor as Roman cataphract. In this picture, the rider has discarded his contus (lance) and unsheathed his sword for mêlée combat] [ [http://s85.photobucket.com/albums/k75/dogpng1/KOLR/ Roman cavalry pictures] , photobucket.com. "Retrieved" 7 February 2008] A deserter from the "Scutarii" regiment informed Chnodomar of Julian's plan to march to Strasbourg. Chnodomar thus had the advantage that he could choose the battlefield. He selected a hill of modest height covered in wheat fields a few miles from the Rhine. [Ammianus XVI.12.19] Libanius claims that on one side was an "elevated water course" (presumably an aqueduct or canal), built over a swamp. [Libanius 140] But this seems incompatible with Ammianus' statement that the battle took place on higher ground (as water could hardly flow uphill), and may be a garbled detail from another of Julian's battles. The site of the battlefield is dictated by Ammianus' statement that Julian's army marched 21 Roman miles (32 km) from Saverne along the Metz-Strasbourg highway. [Ammianus XVI.12.8] One theory is that the battle took place at the site of the village of Oberhausbergen 3km NW of Strasbourg. [Drinkwater (2007) 237] This lies about 1km north of the Roman highway from Severne (today the D228 road). If this was the site, then the Romans would have faced the Alamanni ranged at the top of Oberhausbergen hill, with the highway to the Roman rear. But it is as likely that the battlefield was in Koenigshoffen, a western suburb of modern Strasbourg, which lies astride the Roman highway. [IGN "Carte de Promenade" 12 (Strasbourg/Forbach)]

The campaigning season was by now well-advanced, as Julian had spent a considerable time restoring Saverne. But it was still summer, as the weather was hot and wheat was ripe in the fields. [Ammianus XVI.12.11, 19] It was therefore probably August. Julian's army covered the distance to Strasbourg in the morning, arriving within reach of the enemy at around noon. [Ammianus XVI.12.11] Chnodomar, alerted by his lookouts that the Roman army was in sight, moved his army forward from its base before the ruined walls of Strasbourg to his chosen battlefield nearby. [Ammianus XVI.12.19]

A short distance from the battlefield, Julian called a halt for rest and refreshment. Concerned that his men might be too tired to fight after a long march in the hot sun, he proposed to make camp and postpone the clash until the following day. But his officers and men would have none of it and clamoured to be led against the enemy that same day. Julian, who prided himself on acting by consensus, gave way. [Ammianus XVI.12.8-13] It is an indication of the extraordinary stamina of Roman soldiers that they could even contemplate fighting what was likely to be a very arduous battle after a 20-mile march in full battle attire.

Advancing along the highway to the battlefield, the Romans found the German host already drawn up, probably in a dense mass and on the crest of the hill, to give Chnodomar's men the advantage of the slope. [ Elton (1996) 81] The German left wing was held by Chnodomar and his cavalry and the right wing was under his nephew Serapio (who was given his Greek name by his Hellenophile father). Although still a teenager, Serapio had already proved a military leader worthy of his uncle. [Ammianus XVI.12.19] [Goldsworthy (2000) 176] The rest of the line was under five major kings and ten petty kings. In shrubland on the German right flank were the Germans hidden in ambush by Chnodomar.

The Roman infantry was drawn up in two lines and the cavalry (estimated at ca. 3,000) on the right flank. On the left flank were posted Severus' separate division. [Goldsworthy (2000) 176]

As soon as the two armies were drawn up, a clamour arose from the German ranks, loudly demanding that Chnodomar and his entourage of chiefs should dismount and lead the main body of German foot warriors from the front. Chnodomar and the chiefs immediately complied. [Ammianus XVI.12.34-5] In so doing, Chnodomar forfeited any strategic control of the battle, as, trapped in the centre of the action, he would have no way of knowing what was happening in other sectors. Julian, on the other hand, maintained a detached position throughout (with his escort) and so was able to respond to events all over the field, such as the initial rout of his cavalry. It is unclear exactly where Julian was stationed but it was likely in the gap between the two Roman lines. [Goldsworthy (2000) 176]

The Roman cavalry engaged the German horsemen, but Chnodomar's stratagem paid dividends. The interspersed foot warriors wreaked havoc, bringing down the horses of the "cataphracti" and then killing their riders on the ground. Disconcerted by these tactics, the Roman cavalry panicked and fled the field. In their headlong flight, the "cataphracti" crashed into the Roman infantry on the right, which only held steady because of the skill of the crack "auxilia palatina" regiments "Cornuti" and "Brachiati" posted there. The Roman cavalry took refuge behind the infantry lines, where it took the personal intervention of Julian himself to rally them. [Ammianus XVI.12.37-8] Zosimus claims that one regiment of "cataphracti" refused to return to the fight and that after the battle, they were obliged by Julian to wear female clothes as punishment. [Zosimus III.68] (This lenient sanction for an offence that would by Roman tradition warrant decimation, was probably due to Julian's severe shortage of troops). The first critical moment of the battle had been reached, as the Roman front line's right flank was now exposed to assault by the victorious German cavalry. But the right wing, reinforced by the "Reges" and "Batavi" regiments, which moved forward from the right wing of the rear line, held formation. Together, these regiments managed to defend the Roman right wing until the regrouped Roman cavalry returned to relieve the pressure on the flank. [Ammianus XVI.12.43-5]

In the meantime, on the Roman left wing, Severus must have suspected the prepared ambush, and held back from advancing into the rough ground. Libanius contradicts this, claiming that the Romans charged the enemy and flushed them out of their hiding places. [Libanius 140] But Ammianus' version is more likely, as the Romans would hardly have benefited by advancing straight into a prepared trap. Ammianus does not report further action in this sector. But it is likely that the hidden Germans eventually lost patience, advanced out of the woods and charged at Severus' division, only to be routed by Severus' crack troops. [Goldsworthy (2000) fig. on p. 176]

In the centre, the German foot warriors repeatedly charged straight at the serried ranks of Romans, hoping to break through by sheer weight of numbers. But the Roman front line held for a long time, inflicting severe casualties on the Germans who flung themselves recklessly at the massed spears. Then, a group of German chiefs and their best warriors formed a dense mass, and, let through by the German front ranks, charged the Romans. This may have been a barbarian formation known as a hogshead, a wedge protected by armoured warriors on the outside. They succeeded, by desperate efforts, in punching a hole through the centre of the Roman front line. [Ammianus XVI.12.46-50] This was potentially disastrous for the Romans. But despite being cut in two, the Roman front line evidently did not collapse: the experienced frontline regiments managed to hold their separated wings in formation.

Meanwhile, a large number of Germans poured through the breach and charged the centre of the Roman rear line. This position was held by the elite Primani legion, which stopped the German attack in its tracks and then counterattacked, routing the breakthrough. [Ammianus XVI.12.49] The breach in the front line was presumably filled, either by the separated wings of the front line reconnecting, or by the Primani from the rear line (Ammianus does not specify which). The front line, now extended on the left flank by the rear line left wing, (and presumably by Severus' victorious division), began pushing the Germans back, and gradually hemmed them in from the flanks. At this point, the Germans were already exhausted and demoralised by their lack of progress and severe losses. The mass of their army was now trapped in an ever-tighter Roman crescent, with the troops on the edges being methodically cut down and the ones in the middle packed tightly together and unable to move. Finally, after more relentless pressure from the Romans, the German line collapsed: as panic spread through their ranks, the Germans broke formation and ran for their lives. [Ammianus XVI.12.50-1] Many did not run fast enough: pursued all the way to the Rhine by Roman cavalry and infantry, many were cut down as they ran. Large numbers attempted to swim across the river, but many drowned, hit by Roman missiles or weighed down by their armour. [Ammianus XVI.55-6]

Ammianus reports that 6,000 Germans perished on the battlefield and in the pursuit on land. (Libanius gives a figure of 8,000). [Libanius 141] Thousands more drowned as they tried to get across the river. It is thus likely that about a third of the German force lost their lives. However, it appears that the majority escaped, including the six "reges" alongside Chnodomar. The Romans lost just 243 men, including four "tribuni" (regimental commanders) of which two were commanders of "cataphracti". Chnodomar himself and an escort of 200 men tried to escape by reaching some boats prepared for just such an emergency near the wrecked Roman fort of "Concordia" (Lauterbourg), some 40 km downstream from Strasbourg. But they were cornered by a Roman cavalry squadron in a wood on the bank of the Rhine and surrendered. Brought before Julian, whom he begged for mercy, Chnodomar was sent on to the court of Constantius at Milan. Not long afterwards, he died of disease in a camp for barbarian prisoners in Rome. [Ammianus XVI.12.58-61; 65-6]

After the battle, Julian was acclaimed as "Augustus" (emperor) by his troops. But he vehemently refused the title, which could only legally be bestowed by the ruling "Augustus", Constantius. [Ammianus XVI.12.64] Given the latter's murderous attitude against potential contenders, Julian's caution is understandable.

Aftermath

The immediate aftermath of the battle saw a vigorous "ethnic cleansing" campaign as all Alamanni who had settled in Alsace were rounded up and expelled from imperial territory. [Ammianus XVII.11.2]

The battle was the turning point in Julian's effort to restore the Rhine frontier. Until then, Julian was obliged to campaign largely inside Gaul, with the barbarian bands holding the initiative, playing cat-and-mouse with his forces and causing enormous economic damage to a vital region of the empire. Starting with the 358 campaigning season, Julian was able to take the war to the enemy, each year invading the lands beyond the Rhine, devastating them and terrorising the tribes into accepting tributary status. At the same time, he was able to make serious progress in repairing Rome's shattered line of forts. In Luttwakian terms, he was able to return to a traditional strategy of "forward defence" after being obliged by circumstances to engage in defence-in-depth for three years.

Still in 357, Julian followed up the battle by an incursion into Alamanni territory beyond the Rhine. After ravaging the lands far and wide, he set about rebuilding a fort in the "Agri Decumates" (Black Forest) originally built by Trajan in the early 2nd century. He then granted the anxious barbarians a 10-month truce. [Ammianus XVII.1]

In 358, Julian first turned his attention to the Frankish tribes, crossing the lower Rhine and forced the Salii and Chamavi tribes to surrender and become "tributarii" (tribute-payers). [Ammianus XVII.8] He then restored three important forts on the lower Meuse river. [Ammianus XVII.9] Finally, he switched his attention to the Alamanni, crossing the Rhine at Mainz and forcing the submission of the new paramount kings Hortarius and Surmarius. [Ammianus XVII.10]

In 359, Julian restored seven forts and town walls in the middle Rhine, including "Bonna" (Bonn) and "Bingium" (Bingen), obliging his new tributary Alamanni to provide the supplies and labour needed. He then crossed the Rhine, marched through the territory of the tributaries and devastated the lands of the other kings who had fought at Strasbourg, including Westralp. All were forced to submit and return the thousands of Roman civilians they had abducted and enslaved during the years of easy plunder. [Ammianus XVIII.2]

In 360, his final campaigning season in Gaul, Julian was again proclaimed "Augustus" by his troops. He again refused, but this time, the troops insisted, making it clear they would mutiny and march against Constantius. Alarmed, but also secretly pleased, Julian wrote an apologetic letter to Constantius explaining why he had felt it necessary to bow to his soldiers' wishes and asking for his ratification. But Constantius replied demanding that Julian revert to "Caesar" status. [Ammianus XX.4-9] Julian ignored the order, but in order to prove his good faith and also to keep his near-mutinous troops occupied, he crossed the Rhine and attacked the Attuarii tribe of the Frankish confederation. [Ammianus XX.10] The following year, the two emperors marched against each other to settle the issue. But the empire was spared another civil war by the senior emperor's sudden death in Asia Minor (361).

As sole emperor (361-3), Julian succumbed, as so Roman leaders before him (e.g. Crassus, Trajan, Septimius Severus) to "Alexander the Great syndrome": the desire to emulate the Macedonian general and conquer the Persian empire. He invaded Mesopotamia at the head of an enormous army of 65,000. [Ammianus XXIV] But the campaign was a disaster: Julian lost his own life and his army was forced to retreat with huge losses. [Ammianus XXV] Although most of these would have been from the eastern "comitatus" and from the emperor's own escort army, the "comitatus" of Illyricum and Gaul would undoubtedly have been stripped of troops to fill the gaps. The result was that in 366 Gaul was again overrun by Alamanni hordes and Julian's painstaking work of restoration undone. This forced Julian's successor, Valentinian I, to spend years carrying out a virtual replay of Julian's Gallic campaign. [Ammianus XXVII, XXVIII]

Roman order of battle

The composition of Julian's army at Strasbourg can only be partially reconstructed. Ammianus gives the names of only five regiments in his account of the battle itself. But at other points of Ammianus' narrative of Julian's campaigns in Gaul, and also in Zosimus' history, there are mentions of other regiments in his "comitatus", which were very likely at Strasbourg also.

A "comitatus" at this time probably contained only three types of regiment, all of them of the top, palatini, grade: cavalry "vexillationes" and infantry "legiones" and "auxilia". [Jones (1964) 97, 125] There is much uncertainty about the size of late Roman army units. The official strength of "vexillationes" and "legiones" seems to have been 800 and 1,200 respectively. But actual strengths recorded were 400 and 800 respectively. [Elton (1996) 89] A midpoint between these figures is assumed here of 500 for "vexillationes" and 1,000 for "legiones palatinae". The strength of the "auxilia palatina" regiments is disputed. They may have been as large as legions, or only half the size. [Goldsworthy (1995) 206] Half the size is more likely, as it accords best with the available evidence. [Jones (1964) 682] [Elton (1996) 90 note 3] Also, if an "auxilium" was the same size as a legion, there would seem little purpose in the distinction between the two types of unit.

The sources give the following units for Julian's "comitatus":

NOTE: Asterisk indicates unit specified by Ammianus at Strasbourg

The "Ioviani" and "Herculiani" legions and "equites Dalmatae" are not mentioned by the sources as under Julian, but as part of the Gaul "comitatus" of usurper Magnentius. They are likely to have been inherited by Julian. If all these units were present at Strasbourg, the infantry total is 1,500 short. Probably the names of 3 "auxilia" regiments are missing in our sources. If so, at least one of them is likely to be a "sagittarii" (archer) unit, as a "comitatus" would be incomplete without archer capacity. Overall, the most likely scenario is that Julian's force at Strasbourg consisted of 5 "legiones" and 10 "auxilia" of infantry and 6 "vexillationes" of cavalry.

As regards cavalry, Ammianus mentions only "cataphracti" in his account of the battle. But it is virtually certain that they were only part of his force. In the late army as a whole, only 15% of cavalry regiments were heavily armoured "cataphracti". These were suitable for the shock charge. Two "tribuni" (regimental commanders) of cataphracts were reported killed at Strasbourg. There were thus at least two "vexillationes" of cataphracts (1,000 horse) engaged. Elsewhere in Ammianus and Zosimus it is stated that Julian had a regiment of "Gentiles" and a regiment of "scutarii" under his command. Both these were normal (semi-armoured) units that represented the majority (61%) of the late army's cavalry and were best suited to mêlée combat. There is also mention of light (unarmoured) units of "equites Dalmatae" and "equites sagittarii" (mounted archers). Light cavalry was used for harassment and pursuit. The likeliest scenario is that all these were present at Strasbourg, with 2 "vexillationes" each of heavy, normal and light cavalry engaged. It is thus likely that cataphracts were about a third of Julian's cavalry at Strasbourg. In addition, Julian had a personal escort of 200 picked cavalry. [Ammianus XVI.12.28] These were probably a detachment from one of Constantius' "scholae" (elite cavalry squadrons, believed 500 strong, that served as the imperial horse guard).

As regards the line of battle, we are given a little information by Ammianus. He reports that the right flanks of each line, front and reserve, were held by 2 "auxilia" regiments and the centre of the reserve line was held by the "Primani" legion. Goldsworthy assumes that the two lines were equal in strength. [Goldsworthy (2000) fig on p.176] But this is not actually stated in the sources, and it was quite possible that the reserve line would have been smaller than the front line. Libanius states that the legions were stationed in the centre of the line. [Libanius 139] This is consistent with the position of the "Primani" given by Ammianus. A possible line-up that fits the fragmentary evidence may be devised. Front line: centre held by 3 legions, flanks each held by 2 "auxilia", the right flank by the "Cornuti" and "Brachiati" (total: 5,000). Reserve line: centre held by "Primani" legion, flanks by 3 "auxilia" each, the right including the "Reges" and "Batavi" (total: 4,000). The remaining legion (1,000) would form Severus' separate division on the left.

It is difficult identify any of the units mentioned above with those listed in the "Notitia Dignitatum", a late Roman manual of administrative and military posts, whose western part was drawn up in the 420's. Firstly, the sources do not specify the numbers of the cavalry regiments at Strasbourg. For example, there were several units of "equites Dalmatae" and "equites sagittarii". For the infantry, the main difficulty is the emergence of regiments with the same name, but with the additional title of "seniores" or "iuniores". This feature applies to about 100 elite regiments in the "Notitia". The timing, origin and purpose of the new titles are uncertain (see Late Roman army). Its first attested use is dated 356 ("Iovii Cornutes Seniores"). [Elton (1996) 95] But if it already existed in Julian's time, then Ammianus fails to specify whether his units were "seniores" or "iuniores", making specific identification with "Notitia" units impossible.

Within these constraints, it is possible to identify some units in the "Notitia" as likely the same as, or descendants of, the regiments at Strasbourg. For cavalry, the Emperor in the West had one "schola Gentilium" under his command. ["Notitia Dignitatum" Title Occ. IX] Ammianus does not specify if the "Gentiles" regiment he mentions was a "schola". It may have been just a "vexillatio palatina" which was later upgraded to a "schola". The "magister equitum Galliarum" commanded the vexillation "equites VIII Dalmatae" ("8th Dalmatian cavalry"). The "comes Britanniarum", whose units probably originated in the Gaul "comitatus" commanded the vexillations "equites cataphractarii iuniores" and "equites scutarii Aureliaci" ("Aurelian Shield-Bearer cavalry", probably named after the emperor Aurelian, ruled 270-5). ["Notitia" Title Occ. VII] For infantry, the "magister equitum" in Gaul commanded the "auxilia palatina" "Brachiati iuniores" and "Batavi iuniores" and the "comes" in Britain the legion "Primani iuniores". The other regimental names are represented in the escort army of the "magister peditum" in Italy. These include the following "seniores" regiments: "legiones": "Ioviani", "Herculiani", "Moesiaci", "Pannoniciani". The latter two units could be the two Moesian legions in Ammianus. "Auxilia palatina": "Batavi", "Cornuti", "Brachiati", "Heruli", "Petulantes", "Celtae". The Italian army also contained a "legio comitatensis" called the "Regii". ["Notitia" Title Occ. V] Goldsworthy assumes this the same unit as the "Reges" mentioned by Ammianus. [Goldsworthy (2000) 176] But it may not be. Apart from the different declension, the "Reges" were an "auxilium palatinum", not a legion.

Alamanni forces

At Strasbourg, there were 9 "reges" (kings): Chnodomar and his nephew Serapio; Westralp, Urius, Ursicinus, Hortarius, Suomarius; [Ammianus XVI.12.1] and the two treaty-breakers Vadomar and his colleague. Each would probably have had two "pagi" under him making a total of 18 "pagi". If we assume the non-Alamanni levies, as Drinkwater does, at 25 %, that leaves ca. 26,000 Alamanni warriors at Strasbourg: roughly 1,500 per "pagus". The total population of the Alamanni was ca. 135,000 (midpoint between 120-150,000), so each "pagus" would on average contain ca. 7,500 people. So 20% of the "pagus" population would have been levied for Strasbourg. Elton shows that up to 25% warriors in a barbarian population is realistic.

Citations

References

Ancient

* Ammianus Marcellinus "Res Gestae" (late 4th c.)
* Libanius "Funeral Oration for Julian" (363 AD)
* Zosimus "Nova Historia" (late 5th c.)

Modern

* Drinkwater, J. F. (2007) "The Alamanni and Rome (213-496)"
* Elton, Hugh (1996), "Roman Warfare 350-425"
* Goldsworthy, Adrian (2000), "Roman Warfare"
* Jones, A. H. M. (1964), "Later Roman Empire"
* Raddatz, K. (1967), "Die Bewaffnung der Germanen in der jüngeren römischen Kaiserzeit" [German]
* Speidel, M. (2004), "Ancient Germanic warriors, warrior styles from Trajan's column to Icelandic sagas"

Further reading

* Karlheinz Fuchs, Martin Kempa, Rainer Redies: "Die Alamannen", Theiss Verlag, Stuttgart 2001, ISBN 3-8062-1535-9. "Ausstellungskatalog"
* Dieter Geuenich: "Geschichte der Alemannen", Verlag Kohlhammer, Stuttgart 2004, ISBN 3-17-018227-7/ISBN 3-17-012095-6.

See also

Late Roman army