Caesar's Rhine bridges - AbsoluteAstronomy.com

Caesar's Bridge across the Rhine, the first two bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

s to cross the Rhine River, were built by Julius Caesar

Julius Caesar

Gaius Julius Caesar was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire....

and his legionaries

Roman legion

A Roman legion normally indicates the basic ancient Roman army unit recruited specifically from Roman citizens. The organization of legions varied greatly over time but they were typically composed of perhaps 5,000 soldiers, divided into maniples and later into "cohorts"...

during the Gallic War in 55 BC

55 BC

Year 55 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Crassus and Pompey...

and 53 BC

53 BC

Year 53 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Messalla and Calvinus...

, respectively. Strategically successful, they are also considered masterpieces of military engineering

Roman military engineering

The military engineering of Ancient Rome's armed forces were of a scale and frequency far beyond that of any of its contemporaries'. Indeed, military engineering was in many ways institutionally endemic in Roman military culture, as demonstrated by the fact that each Roman legionary had as part of...

Background

During the conquest of Gaul

Gaul

Gaul was a region of Western Europe during the Iron Age and Roman era, encompassing present day France, Luxembourg and Belgium, most of Switzerland, the western part of Northern Italy, as well as the parts of the Netherlands and Germany on the left bank of the Rhine. The Gauls were the speakers of...

it became necessary to secure the eastern border of the new provinces against marauding Germanic tribes. The tribes felt safe on the eastern side of the Rhine river, trusting the river as a natural border

Natural border

A natural border is a border between states which is composed of natural formations such as rivers, mountain ranges, or deserts.Having a natural border is strategically very useful, as invading armies can have a hard time crossing such a border...

which offered cover from retaliatory attack after their opportunistic raids into the province. Caesar decided to confront them. He also wanted to show support for the Ubii

Ubii

thumb|right|350px|The Ubii around AD 30The Ubii were a Germanic tribe first encountered dwelling on the right bank of the Rhine in the time of Julius Caesar, who formed an alliance with them in 55 BC in order to launch attacks across the river...

, an allied German tribe across the Rhine. While he could have crossed the Rhine by boat, he decided to build a bridge. By this he demonstrated the might and power of Rome. In addition, as he indicated in his Commentary on the Gallic War

Commentarii de Bello Gallico

Commentarii de Bello Gallico is Julius Caesar's firsthand account of the Gallic Wars, written as a third-person narrative. In it Caesar describes the battles and intrigues that took place in the nine years he spent fighting local armies in Gaul that opposed Roman domination.The "Gaul" that Caesar...

, this approach conformed more to the dignity of the Roman Army

Roman army

The Roman army is the generic term for the terrestrial armed forces deployed by the kingdom of Rome , the Roman Republic , the Roman Empire and its successor, the Byzantine empire...

Construction

The first bridge

The actual construction of Caesar's first bridge took place most likely between Andernach

Andernach

Andernach is a town in the district of Mayen-Koblenz, in Rhineland-Palatinate, Germany, of currently about 30,000 inhabitants. It is situated towards the end of the Neuwied basin on the left bank of the Rhine between the former tiny fishing village of Fornich in the north and the mouth of the...

and Neuwied

Neuwied

Neuwied is a town in the north of the German state of Rhineland-Palatinate, capital of the District of Neuwied. Neuwied lies on the right bank of the Rhine, 12 km northwest of Koblenz, on the railway from Frankfurt am Main to Cologne...

, downstream of Koblenz

Koblenz

Koblenz is a German city situated on both banks of the Rhine at its confluence with the Moselle, where the Deutsches Eck and its monument are situated.As Koblenz was one of the military posts established by Drusus about 8 BC, the...

on the Rhine River. Book 4 (Liber IV) of his commentaries gives technical details of this wooden beam bridge

Beam bridge

Beam bridges are the most simple of structural forms being supported by an abutment at each end of the deck. No moments are transferred through the support hence their structural type is known as simply supported....

. Double timber pilings were rammed into the bottom of the river by winching up a large stone and releasing it, thereby driving the beam into the riverbed. The most upstream and downstream pilings were slanted and secured by a beam, and multiple segments of these then linked up to form the basis of the bridge. Conflicting models have been presented based on his description. Separate upstream pilings were used as protective barriers against flotsam and possible attacks while guard towers protected the entries. The length of the bridge has been estimated to be 140 to 400 m (roughly 460 to 1,300ft), and its width 7 to 9 m (23 to 30ft). The depth of the river can reach up to 9.1 m (30ft).

The construction of this bridge showed that Julius Caesar, and Rome, could go anywhere. Since he had over 40,000 soldiers at his disposal, they built the first bridge in only 10 days using local lumber. He crossed with his troops over to the eastern site and burned some villages but found that the tribes of the Sugambri and Suebi

Suebi

The Suebi or Suevi were a group of Germanic peoples who were first mentioned by Julius Caesar in connection with Ariovistus' campaign, c...

had moved eastward. After 18 days and without any major battle he returned to Gaul and cut the bridge down.

The second bridge

Two years later, close to the site of the first bridge, possibly at today's Urmitz

Urmitz

Urmitz is a municipality in the district of Mayen-Koblenz in Rhineland-Palatinate, western Germany....

(near Neuwied

Neuwied

), Caesar erected a second bridge, built "in a few days", as described in Book 6 (Liber VI). His expeditionary forces raided the country side, but did not encounter significant opposition as the Suebi retreated. Upon returning to Gaul, the bridge was again taken down.

Results

Caesar's strategy was effective, as he was able to secure the eastern border of Gaul. He demonstrated that Roman power could easily and at will cross the Rhine and henceforth for several centuries significant Germanic incursions across the Rhine were halted. Further, his feat served him in establishing his fame at home.

With Roman colonization of the Rhine valley more permanent bridges were built later at Castra Vetera (Xanten

Xanten

Xanten is a historic town in the North Rhine-Westphalia state of Germany, located in the district of Wesel.Xanten is known for the Archaeological Park or archaeological open air museum , its medieval picturesque city centre with Xanten Cathedral and many museums, its large man-made lake for...

), Colonia Claudia Ara Agrippinensium

Colonia Claudia Ara Agrippinensium

Colonia Claudia Ara Agrippinensium was the name of the Roman colony in the Rhineland out of which the German city of Cologne developed.It was the capital of the Roman province of Germania Inferior and the headquarters of the military in the region. With the administrative reforms under Diocletian,...

(Cologne

Cologne

Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...

), Confluentes (Koblenz

Koblenz

), and Moguntiacum (Mainz

Mainz

Mainz under the Holy Roman Empire, and previously was a Roman fort city which commanded the west bank of the Rhine and formed part of the northernmost frontier of the Roman Empire...

Controversies about the location

Speculation about the location of the bridges is due to the temporary nature of the construction and the lack of a precise location in Caesar's report. However, diggings in the Andernach-Neuwied area found residual pilings that are considered to be remnants of Caesar's bridges. As an alternative site a place south of Bonn

Bonn

Bonn is the 19th largest city in Germany. Located in the Cologne/Bonn Region, about 25 kilometres south of Cologne on the river Rhine in the State of North Rhine-Westphalia, it was the capital of West Germany from 1949 to 1990 and the official seat of government of united Germany from 1990 to 1999....