Argentovaria, also known as Ödenburg, is the collective term for a late Roman military installation and a civilian settlement in the area of Biesheim in Alsace, France.
The ancient sites of Biesheim-Kunheim and Ödenburg-Altkirch owe their importance to their position at an important crossing over the Rhine. In the 1st and the 4th centuries AD the area was dominated by the military, but in the 2nd and 3rd centuries AD, the civilian settlement came to the fore. During the great barbarian invasions in the 4th and 5th centuries AD Argentovaria was probably part of a chain of forts that also included the fortifications on the right bank of the Rhine on the Münsterberg in Breisach and on the Sponeck in Sasbach am Kaiserstuhl.
The late Roman castrum was probably one of the numerous border fortresses built under Emperor Valentinian I in the final phase of Roman rule over the Rhine provinces, but only briefly occupied. It was part of the chain of forts of the Danube-Iller-Rhine Limes in the section of the Maxima Sequanorum province. The fort was probably occupied by Roman troops from the 4th to the 5th century AD who were responsible for security and surveillance tasks along the Rhine border.
Name The ancient name of the civil settlement and the fort are known to us from the second century geographer Claudius Ptolemy and from the Tabula Peutingeriana. Inscriptions supporting this name have not yet been discovered. Around the year 150 Ptolemy referred to the civil settlement of Argentovaria as the "second polis" of the Celtic Rauraci people after Augusta Raurica. The current name "Altkirch" (popularly "Kirchenbuckel") derives from a medieval church which, together with its cemetery has been identified west of the south gate of the fort.
Location Biesheim is about halfway between Basel and Straßburg, north of Neuf-Brisach and exactly opposite the Kaiserstuhl mountain range. The mountain ranges of the Vosges and the Black Forest, in connection with the strongly meandering Rhine, were considerable obstacles to travel, and to this day only allow east–west passage in a few places. The late antique fort is located on the left bank of the Rhine, a little northwest of the fort at Breisach. The archaeological sites are north of Biesheim. Maps from the 16th and 17th centuries show a place called Edenburg, Oedenburg or Oedenburgheim, which was destroyed in the Thirty Years' War and not rebuilt afterwards. The first wood and earth fort that can be identified here stood on an island on the Rhine, which offered good natural protection. The area of the later fort is currently used intensively for agriculture, and is only recognizable by the relief of the terrain. The fortification was located directly east of the Limes road (via puplica), close to the subsidence of what was then the banks of the Rhine, and was therefore easily accessible by land and also by ship. The findings indicated that as a result, the fort was hit by floods more frequently. Today only the Riedgraben Canal passes here, a sparse remnant of the ancient river bed. The border line between the two Rhine provinces Germania Prima and Maxima Sequanorum ran north of the Kaiserstuhl mountains. Along this line a road from Biesheim-Oedenburg that crossed the Vosges and Divodurum (Metz) and reached the bank of the Rhine. Here it subsequently crossed with the Limes road on the left bank of the Rhine, running from north to south. The fort probably had a strong relationship to this road network.
Research history Ödenburg is mentioned for the first time by Beatus Rhenanus in 1551 and also appears on Daniel Specklin's map in 1576. Roman finds have been known since around 1770. Originally, Horbourg-Wihr, a district of the municipality of Horbourg near Colmar in the French Département Haut-Rhin, seen as the site of the ancient Argentovaria. However, this assumption had to be revised based on the latest research results. In the late 1970s and early 1980s scientific excavations took place in the southern area of the medieval cemetery for the first time, whereby the area of the late antique fortress was also excavated, although it was not recognized as such. From 1998 to 2002 geophysical soil measurements were carried out as part of the trinational archaeology project “Ödenburg-Altkirch” (Eucor program). After evaluation, targeted excavations by scientists from the University of Freiburg and the University of Basel under the direction and coordination of Hans Ulrich Nuber and of Michel Reddé from the University of Paris became possible. The aim was to further supplement the knowledge about the ancient settlement of the area of Ödenburg-Altkirch, including the military camp, praetorium, civilian town, and Gallo-Roman temple district, from the first to the fourth centuries AD. The excavations were also accompanied by paleobotanical and zoological studies. In the course of these excavations the late Roman fortifications and a group of buildings in the adjacent area “Westergass” were discovered. By 2001, international excavation teams moved almost of earth and uncovered 470 finds, by which the course of the north wall could be precisely determined. From 2003 to 2005 École pratique des hautes études, together with the University of Freiburg and Peter-Andrew Schwarz and Caty Schucany from the University of Basel carried out excavations on the area of the Gallo-Roman temple district in Biesheim-Kunheim. Numerous new insights into ancient cult practices (modus munificendi) were gained. In front of the fort some ancient building remains of the town from the end of the first century AD, which had been destroyed by fire, were uncovered.
Development The region around Biesheim has been settled since pre-Roman times. Along with Augusta Raurica (Kaiseraugst), Argentovaria was probably one of the largest oppida (caput civitatis) of the Rauraci. To keep the population under control the Romans built a simple wood-earth fortification at this strategically important site. The Roman civilian settlement did not develop around this early fort, but around the temple area from 20 AD.
The wood and earth fort was founded in the 1st century AD, the late antique fort was probably built between 369 and 370 during the reign of Emperor Valentinian I (364–375) in the course of the last expansion and strengthening measures on the Rhine Limes. It belonged to a fortress belt (claustra/clausurae), which consisted of the forts Breisach / Münsterberg (Mons Brisiacum), Sasbach-Jechtingen, and Horbourg and probably also included an Alemannic fortification on the Zähringen castle hill.
The wood-earth forts of the 1st century may have served as a staging area and deployment base for campaigns in the areas on the right bank of the Rhine. The duties of the garrison in Argentovaria were probably to monitor road traffic, control shipping traffic on the river, and watch over the Rhine crossing. Other activities included the observation of the barbarians on the right bank of the Rhine, daily patrols, and the transmission of messages and signals along the Limes.
In the years between 259 and 260, Alemannic tribes finally overran the Upper Germanic-Raetian Limes. Then they occupied the Agri Decumates, which had been under Roman rule for more than 200 years. After the Crisis of the 3rd Century, the Romans were able to stabilize the border along the Rhine, Lake Constance, Iller and Danube lines again. Here, from the late 3rd century, the emperors Diocletian and Maximian built the chain of forts of the so-called Danube-Iller-Rhine Limes. Nevertheless, the Alemanni repeatedly invaded the territory of the Empire, since they often exploited the internal power struggles of the Romans which were usually associated with an almost complete withdrawal of the Limes troops.
In 357 the Battle of Argentoratum took place near what is now Strassburg, in which Emperor Julian the Apostate succeeded in routing the Alemanni and taking their King Chnodomar prisoner. In 378, allegedly 40,000 Alemannic Lentienses broke through the Rhine Limes—either directly at the Sponeck crossing or near Breisach—devastating the border areas and penetrating into the interior of Gaul. To defend his own territory the Western Emperor, Gratian, had to recall a large part of his army from Illyricum, whence it had been dispatched to assist his uncle, the Eastern Emperor, Valens against the Goths and Alans invading Thrace. The invading Alemanni were soon thrown back across the Rhine by Gratian and his Frankish military leaders, the comes Nannienus and the comes domesticorum Mallobaudes after the nearby Battle of Argentovaria, but this victory cost Valens dearly, since Gratian then arrived too late in the Balkans, to save Valens from the catastrophic defeat at the Battle of Adrianople. In August 369 Emperor Valentinian I was staying in the neighboring fort Mons Brisiacum, from where he could, at least temporarily, coordinate and monitor the large-scale construction activities of the Romans on the Rhine Limes. In the course of this, the fortress in Argentovaria was built. Judging by the number of coins, it existed until the withdrawal of the regular border troops under Stilicho between 401 and 406, and possibly even until the middle of the 5th century.
The ruins of the fort were probably still visible above ground until the end of the 17th century. From 1701 on it was removed to extract stone material for the construction of the Neuf-Brisach fortress.
Fort
A Roman military base had existed in Biesheim since the 1st century AD. Altogether, two Julio-Claudian wood and earth forts were found for this period, but they were abandoned in the late 1st century. Hans Ulrich Nuber suspects another predecessor from the time of Augustus under the late antique fort.
Oedenburg-Altkirch represents a new type of fort within the comprehensive late antique fortress construction program. The Valentinian castrum measured , was precisely aligned with the cardinal points, had a square floor plan, and covered an area of approximately . The building material consisted for the most part of tephrite, a type of volcanic rock found in the area. The Roman unit of measurement used in the construction could be determined on the basis of still intact, mortared brick slabs. It was exactly , and thus corresponded to two Gallic pedes Drusani—about . The unusual construction of this fort resembles a much smaller facility of the same time period in the Pfalzel district of Trier (Roman Augusta Treverorum), which has been known as the palatiolum since the Middle Ages. There are clear indications that it was furnished with splendid interior decoration, for example mosaics, and thus could have had a primarily ceremonial function. Similar finds are missing for Oedenburg-Altkirch, but it could have been designed by the same architect.
Defenses