Watchtower Möhlin-Fahrgraben

Watchtower Möhlin-Fahrgraben
Alternative name	Unknown
limes	Danube-Iller-Rhine-Limes
section	Route 2
Dating (occupancy)	Valentinian 4th to 5th century AD
Type	Turres / Burgus
unit	Unknown
size	10 × 10 meters
Construction	stone
State of preservation	Square complex, east and south walls preserved and partially restored.
place	Möhlin
Geographical location	632 701  /  270 850 coordinates: 47 ° 35 '15.1 "  N , 7 ° 52' 24"  O ; CH1903:  six hundred thirty-two thousand seven hundred and one  /  two hundred seventy thousand eight hundred and fifty
Previous	Watchtower Möhlin-Untere Wehren (east)
Subsequently	Watchtower Möhlin-Riburg (west)

Solidus Valentinians I.

The Rhine near Schwörstadt

Findings sketch 1900–1950

Remains of the Burgus wall, as it was in 2012

Images of watchtowers on Trajan's Column

The watchtower of Möhlin-Fahrgraben was part of the Roman Danube-Iller-Rhein-Limes and is located in the municipality of Möhlin in the canton of Aargau in Switzerland .

The late antique watchtowers on the Upper Rhine are among the most important Roman legacies on the territory of today's Switzerland. They were built in the 3rd and 4th centuries and were part of a surveillance and alarm chain that was supposed to secure the southern bank of the Rhine against invaders from free Germania. In the canton of Aargau around 30 watchtowers and other military installations from Roman times have been identified that were part of the fortress line of the Rhine Limes.

location

The watchtower stood on a low gravel terrace that sloped almost perpendicular to the Rhine . A ramp-like, caused by erosion and sloping towards the current gully , on the slope of the so-called driving trench directly at its junction with the Rhine. This location offered a good view of the river and the right bank of the Rhine. Before the Ryburg-Schwörstadt river power plant was built (between 1927 and 1931), there was a landing stage for smaller ships and ferries, after which the trench is named. In the vicinity of the watchtower of Möhlin-Fahrgraben, other such late Roman towers were discovered. The tower at the lower weirs is about 1.5 km away upstream. 3 km downstream is the Bürkli, on which there was probably another such specimen. Other of these towers stood further west at Heimenholz (no longer visible today) and Pfärichgraben . The section of the Rhine border near Möhlin belonged to the province of Maxima Sequanorum in late antiquity .

Research history

The remnants of the watchtower attracted the attention of Ferdinand Keller (1800–1881) in the 19th century , who described them as follows: " ... opposite Niederschwörstadt there are small remnants of a tower hidden in a small ravine in the bushes ." A first excavation was initiated around 1900 by pastor Samuel Burkart. In 1918 Karl Stehlin examined the ruins. Stehlin not only limited himself to the documentation and description of the building structure, but also dug a 14-meter-long exploratory trench. However, there were no indications of the existence of a wall or a surrounding ditch. Conservation work was only carried out in 1950 on the initiative of the Fricktalisch-Badische Vereinigung für Heimatkunde. These included clearing and cleaning measures including scraping out the wall joints and repairing damaged areas on the top of the wall. The separation between antique and restored masonry was marked with Eternit plates. In 1972 further minor renovation work was carried out.

As part of the project "Research, renovation and mise en valeur of the late antique watchtowers in the canton of Aargau", Roman wall remains near Möhlin (AG) were cleaned, documented and analyzed in 2014. In that year, students from the University of Basel (Head: L. Barbieri, D. Reber) again removed the vegetation from the masonry, cleaned it and partially restored it. The smaller part of the two conglomerates of the foundation of the For reasons of conservation, the western wall could only be partially excavated. As an accompanying measure, the lowest stone layers of the rising or the uppermost part of the foundation were exposed and inspections were carried out in the vicinity of the fortifications. In addition, the structural details were documented, a 3D scan of the ruin was created, orthophotos with corrected photogrammetry were made and an information board was set up in 2015. In the course of this investigation, no meaningful or datable finds came to light. Among the earlier finds were fragments of an olive oil amphora (type Dressel 23, origin southern Spain) and a mortar from the late 3rd century AD. This was important during the renovation work on the tower of Möhlin-Fahrgraben, in comparison with two other late antique towers in Canton Aargau, the realization that the towers built under Valentinian I have a lot in common, but in terms of their construction they have a very individual character. B. in relation to the size or the presence of wood reinforcements in the foundation area.

development

With the withdrawal of the army from the Upper Germanic-Raetian Limes , the Romans withdrew the border of the empire in the north to the rivers Rhine ( Rhenus ), Danube ( Danuvius ) and Iller ( Hilaria ) around AD 260 . After the construction of the first fortifications in the late 3rd and first half of the 4th century, Emperor Valentinian I , probably from 369 to 374, left between Basel ( Basileum ) and Lake Constance ( Lacus Brigantiae ) to strengthen the Limes ( ripa ) build another 50 watchtowers ( turres ) and forts ( castra ). They were in visual contact with each other and were used to monitor traffic on the Rhine and, in the event of an alarm, to relay signals to the troops stationed in the Rhine forts ( Riparenses ). These were in this section under the command of the Dux provinciae Sequanicae . In the winter of 401/402 AD, most of the units had to be withdrawn from the Rhine border in order to be able to defend Italy , the heartland of western Rome , against the Visigoths under Alaric . The Rhine towers were not reoccupied afterwards and left to decay. The tower area is now owned by the local community of Möhlin, which celebrated its 100th anniversary in 2013. On this occasion, the municipal council granted a loan for the renovation of the late Roman fortifications.

Watchtower

It was a stone tower or burgus with a square floor plan. The walls on the upstream side and on the arm of the trench were washed down by the Rhine over time and completely destroyed. The remaining remains of the east wall (7.2 meters) and the south wall (7.7 meters) as well as the location of the parts of the west wall that fell into the trench suggest that it was originally around 9.5 × 9.5 meters (outside) or 5.9 × 5.9 meters (inside) dimensions. The foundation was around 1.8 meters wide and around 1.5 meters upwards. The remains of the wall give a good insight into the construction of late antique watchtowers. The investigation of the rising showed that only the two lowest layers of the wall shells are Roman. These are hand blocks made of shell limestone. There are round cavities in the southern and eastern walls, in which there were once three layers of logs that have now completely disappeared. The lowest layer ran parallel to the lines of the wall. The middle layer consisted of pieces of wood laid at right angles on which those of the top layer rested. By installing such wood reinforcements, stones and mortar could be saved, and the latter also dried out faster. The negatives of the middle and top layer of wood can still be seen in the ancient opus caementitium on the edge of the southern wall . A joint in the ancient cast masonry also indicates that some time has passed between the casting of the lower and upper part of the foundation. The gray colored parts of the wall characterize the modern underpinning wall. The reconstruction model of the late antique fort of Kleinbasel ( munimentum robur ) exhibited in the Basel Historical Museum shows such a reinforcement with round timber. They are typical of Valentine fixtures. The cast masonry ( opus caementicium ) was almost entirely bonded with white, very hard lime mortar, which was mixed with stone chips and bricks and small wood chips. How the superstructure of the tower was constructed is unknown. Perhaps it resembled the watchtower Wp 3/15 near the Zugmantel fort, which was reconstructed in the early 1970s . On the Trajan Column in Rome (built 113) the watchtowers ( turres ) on the lower Danube are depicted. There are hay or straw stacks next to them, perhaps they were used to feed the horses and pack animals. A pile of wood was apparently used for the fire signals. A torch is also attached to each tower, which was probably also used to transmit messages. The late Roman watchtowers on the Rhine border could have looked like this or similar.

See also

List of forts in the Danube-Iller-Rhein-Limes

literature

• Walter Drack : The late Roman border weir on the Upper Rhine. Archaeological Guide of Switzerland, No. 13, second revised edition with reference to older literature, Basel 1993, pp. 18–19.
• Peter-A. Schwarz: New research on the Late Antique Upper Rhine Limes in the canton of Aargau I. The watchtowers Koblenz-Kleiner Laufen, Möhlin-Fahrgraben and Möhlin-Untere weirs. With contributions by Sandra Ammann, Sabine Deschler-Erb, Juha Fankhauser, Lukas Freitag, Simon Jeanloz, Tina Lander and Daniel Schuhmann. PDF, pp. 54-57

Remarks

1. ↑ cf. Watchtower Koblenz-Kleiner Laufen , Möhlin-Untere Wehren tower

Web links

Location of the watchtower on Vici.org