Rhine

River Rhine
The Rhine is one of the most important rivers in Europe
Origin	Grisons, Switzerland
Basin countries	Switzerland, Italy, Liechtenstein, Austria, Germany, France, Luxembourg, Belgium, Netherlands
Length	1,320 km (820 mi)
Source elevation	Vorderrhein: approx. 2,600 m (8,500 ft) Hinterrhein: approx. 2,500 m (8,200 ft)
Avg. discharge	Basel: 1,060 m³/s (37,440 ft³/s) Strasbourg: 1,080 m³/s (38,150 ft³/s) Cologne: 2,090 m³/s (73,820 ft³/s) Dutch border: 2,260 m³/s (79,823 ft³/s)
Basin area	185,000 km² (71,430 mi²)

The Rhine (German: Rhein; Dutch: Rijn; French: Rhin; Italian: Reno; Romansh: Rain; Latin: Rhenus; Spanish: Rin) is one of the longest and most important rivers in Europe at 1,320 kilometres (820 mi), with an average discharge of more than 2,000 cubic meters per second. The name of the Rhine comes from the archaic German Rhine, which in turn comes from Middle High German: Rin, from the Proto-Indo-European root *reie- ("to flow"). The Reno River in Italy shares the same etymology.

The Rhine and the Danube formed most of the northern inland frontier of the Roman Empire, and since those days the Rhine has been a vital navigable waterway, carrying trade and goods deep inland. It has also served as a defensive feature, and has been the basis for regional and international borders. The many castles and prehistoric fortifications along the Rhine testify to its importance as a waterway. River traffic could be stopped at these locations, usually for the purpose of collecting tolls, by the state controlling that portion of the river.

Geography

Switzerland

The Rhine's origins are in the Swiss Alps in the canton of Graubünden, where its two main initial tributaries are called Vorderrhein and Hinterrhein. The Vorderrhein (anterior Rhine) springs from Lake Tuma near the Oberalp Pass and passes the impressive Ruinaulta (the Swiss Grand Canyon). The Hinterrhein (posterior Rhine) starts from the Paradies glacier near the Rheinquellhorn at the southern border of Switzerland. One of the latter tributaries originates in Val di Lei in Italy. Both tributaries meet near Reichenau, still in Graubünden. From Reichenau, the Rhine flows north as the Alpenrhein passing Chur and forming the border between Liechtenstein and then Austria on the east side, and canton St. Gallen of Switzerland on the west side, then emptying into Lake Constance. Emerging from Lake Constance, flowing generally westward as the Hochrhein it passes the Rhine Falls and is joined by the Aare river which more than doubles its water discharge to an average of nearly 1,000 cubic meters per second. It forms the boundary with Germany until it turns north at the so-called Rhine knee at Basel.

Germany, France, Luxembourg

The Rhine is the longest river in Germany. It is here that the Rhine encounters some of its main tributaries, such as the Neckar, the Main and later the Moselle, which contributes an average discharge of over 300 cubic meters per second. The north east of France drains to the Rhine via the Moselle and smaller rivers draining the Vosges and Jura uplands. Most of Luxembourg and a very small part of Belgium also drain to the Rhine via the Moselle. Approaching the Dutch border, the Rhine has an annual mean discharge of 2,290 cubic metres per second and an average width of 400 metres (1,300 ft).

Between Bingen and Bonn, the Middle Rhine flows through the Rhine Gorge, a formation created by erosion, which happened at about the same rate as an uplift in the region, leaving the river at about its original level, and the surrounding lands raised. This gorge is quite deep, and is the stretch of the river known for its many castles and vineyards. It is a UNESCO World Heritage Site (2002) and known as "the romantic Rhine" with more than 40 castles and fortresses from the Middle Ages (see links) and many lovely little quaint wine villages.

Until the early 1980s industries were a major source of water pollution. Though many industries can be found along the Rhine up into Switzerland, it is along the Lower Rhine in the Ruhr area that the bulk of them are concentrated, as the river passes the major cities of Cologne, Düsseldorf, and Duisburg. Duisburg is the home of Europe's largest inland port, functioning as a hub to the sea ports of Rotterdam, Antwerp and Amsterdam. The Ruhr, which joins the Rhine in Duisburg, is nowadays a clean river, given the fact that most of industry has disappeared over the last decades. The Ruhr currently provides the region with drinking water. It contributes 70 cubic meters per second to the Rhine. Other rivers from the Ruhr area, above all the Emscher, still carry a considerable degree of pollution.

Netherlands

The Rhine then turns west and enters the Netherlands, where together with the rivers Meuse and Scheldt it forms the extensive Rhine-Meuse-Scheldt delta, one of the larger river deltas in western Europe. Crossing the border into the Netherlands at Spijk, close to Nijmegen and Arnhem the Rhine is at its widest, but the river then splits into three main distributaries: the Waal, Nederrijn ("Lower Rhine") and IJssel.

From here the situation becomes more complicated, as the Dutch name "Rijn" no longer coincides with the main flow of water. Most of the Rhine water (two thirds) flows farther west through the Waal and then via the Merwede and Nieuwe Merwede ( Biesbosch) and, merging with the Meuse, through the Hollands Diep and Haringvliet estuaries into the North Sea. The Beneden Merwede branches off near Hardinxveld-Giessendam and continues as the Noord, to join the Lek near the village of Kinderdijk to form the Nieuwe Maas, then flows past Rotterdam and continues via Het Scheur and the Nieuwe Waterweg to the North Sea. The Oude Maas branches off near Dordrecht, farther down rejoining the Nieuwe Maas to form Het Scheur.

The other third portion of the water flows through the Pannerdens Kanaal and redistributes in the IJssel and Nederrijn. The IJssel branch carries one ninth of the water volume north into the IJsselmeer (a former bay), while the Nederrijn flows west parallel to the Waal and carries approximately two ninths of the flow. However, at Wijk bij Duurstede the Nederrijn changes its name and becomes the Lek. It flows farther west to rejoin the Noord into the Nieuwe Maas and to the North Sea.

The name "Rijn" from here on is used only for smaller streams farther to the north which together once formed the main river Rhine in Roman times. Though they retained the name, these streams do not carry water from the Rhine anymore, but are used for draining the surrounding land and polders. From Wijk bij Duurstede, the old north branch of the Rhine is called Kromme Rijn ("Crooked Rhine") and past Utrecht, first Leidse Rijn ("Rhine of Leiden") and then Oude Rijn ("Old Rhine"). The latter flows west into a sluice at Katwijk, where its waters can be discharged into the North Sea. This branch once formed the line along which the Upper Germanic limes were built. During periods of lower sea levels within the various ice ages, the Rhine took a left turn, creating the Channel River, the course of which now lies below the English Channel.

Large cities

Basel, Strasbourg, Karlsruhe, Mannheim, Ludwigshafen, Wiesbaden, Mainz, Koblenz, Bonn, Cologne, Düsseldorf, Krefeld, Duisburg, Arnhem (Nederrijn), Nijmegen (Waal), Utrecht (Kromme Rijn), Rotterdam (Nieuwe Maas).

Smaller cities

Chur, Konstanz, Schaffhausen, Breisach, Speyer, Worms, Bingen, Rüdesheim, Neuwied, Andernach, Bad Honnef, Königswinter, Niederkassel, Wesseling, Dormagen, Zons, Monheim, Wesel, Xanten, Emmerich, Zutphen (IJssel), Deventer (IJssel), Zwolle (IJssel), Kampen (IJssel)

Railway bridges

Existing and former railway bridges (with nearest train station on the left and right bank):

Vorderrhein

• Switzerland
  • a total of five bridges on the line Andermatt - Reichenau-Tamins (all single tracked, electrified, 1000 mm gauge)

Hinterrhein

• Switzerland
  • a total of two bridges on the line Filisur - Reichenau-Tamins (both single tracked, electrified, 1000 mm gauge)

Alpenrhein

• Switzerland
  • at Untervaz (industrial branch line, single tracked and non-electrifed, combined 1000 mm and 1435 mm gauge)
  • between Bad Ragaz and Maienfeld (double tracked, electrified, 1435 mm gauge)

• Liechtenstein and Switzerland
  • between Schaan and Buchs SG (single tracked, electrified)

• Austria and Switzerland
  • a total of two bridges of the Internationale Rheinregulierungsbahn (both single tracked, electrified, 750 mm gauge)
  • between Lustenau and St. Margrethen (single tracked, electrified)

Hochrhein

• Germany
  • between Konstanz Hbf and Konstanz-Petershausen (single tracked, electrified)

• Switzerland
  • between Etzwillen and Hemishofen (single tracked, non electrified, line closed for traffic)
  • between Feuerthalen and Schaffhausen (single tracked, electrified)
  • between Dachsen and Neuhausen am Rheinfall (single tracked, electrified)
  • between Eglisau and Hüntwangen-Will (single tracked, electrified)

• Switzerland and Germany
  • between Koblenz and Waldshut (single tracked, electrified)

• Switzerland
  • between Basel SBB and Basel Badischer Bahnhof (double tracked, electrified, soon to have four tracks)

Upper Rhine

• France and Germany
  • between Huningue and Weil am Rhein (single tracked, destroyed in WW2)
  • between Chalampé and Neuenburg (single tracked, electrified, freight only - passenger service only on weekends)
  • between Neuf-Brisach and Breisach (single tracked, destroyed in WW2)
  • between Strasbourg and Kehl (single tracked, electrified, soon to be double tracked again)
  • between Roeschwoog and Rastatt-Wintersdorf (double tracked, used as street bridge since 1949, line closed 1960, rails were preserved for strategic purpose until 1999)

• Germany
  

  

  Bridge at Karlsruhe
  • between Karlsruhe-Maxau and Wörth am Rhein-Maximiliansau (double tracked, electrified)
  • between Germersheim and Philippsburg (single tracked, electrified)
  • between Ludwigshafen and Mannheim (four tracks, electrified)
  • between Worms-Brücke and Hofheim (double tracked, electrified)
  • between Mainz-Süd and Mainz-Gustavsburg (double tracked, electrified)
  • between Mainz-Nord and Wiesbaden-Ost (double tracked, electrified)

Middle Rhine

• Germany
  • between Rüdesheim/Geisenheim and Münster-Sarmsheim/Ockenheim (double tracked, destroyed in WW2)
  • between Koblenz Hbf and Niederlahnstein (double tracked, electrified)
  • between Koblenz-Lützel and Neuwied (double tracked, electrified)
  • The bridge at Remagen between Sinzig/Bad Bodendorf and Unkel (double tracked, destroyed in WW2)

Lower Rhine

• Germany
  • two bridges at Cologne:
    • the Südbrücke south of the City (double tracked, electrified)
    • the Hohenzollernbrücke between Köln Hauptbahnhof and Köln Messe/Deutz (six tracks, electrified)
  • between Neuss-Rheinpark Centre and Düsseldorf-Hamm (four tracks, electrified)
  • between Rheinhausen-Ost and Duisburg-Hochfeld Süd (double tracked, electrified)
  • between Moers and Duisburg-Beeck (single tracked (formerly double tracked), electrified, freight only)
  • between Büderich and Wesel (double tracked, destroyed in WW2)

Delta

• Netherlands (in the delta the river splits and its name changes often)
  • between Nijmegen and Elst across Waal (Rhine delta main branch)
  • between Zaltbommel and Geldermalsen across Waal, made famous in a poem by Martinus Nijhoff
  • at Rotterdam across Nieuwe Maas (joint Rhine- Meuse river mouth), former bridge 'De Hef' - now replaced by a tunnel. Farther to the south, main bridge is at Moerdijk.
  • between Elst and Arnhem across Nederrijn (Rhine delta second-largest branch)
  • between Culemborg and Houten across Lek (Rhine delta second-largest branch farther downstream)
  • at Zutphen across IJssel (Rhine third-largest branch)
  • at Deventer across IJssel
  • at Zwolle across IJssel
  • near Alblas across Noord (a branch near Rotterdam), now being replaced by a tunnel.
  • between Utrecht and Zeist across Kromme Rijn (near Bunnik station)
  • at Utrecht central station across Vaartsche Rijn (canal)
  • at Utrecht central station across Oude Rijn (canalised into Leidschse Rijn).
  • between Utrecht and Vleuten, Woerden across Amsterdam Rijn-Canal
  • between Utrecht and Breukelen, Amsterdam across Amsterdam Rijn-Canal

The bridges at Huningue, Rastatt, Rüdesheim (Hindenburgbrücke) and Remagen (Ludendorffbrücke) were built for strategic military reasons only, in order to allow the Imperial German Army (and later the Wehrmacht) to quickly transport forces by rail to Germany's western border in the event of a war with France. Unlike other bridges built for the same purpose (like the ones at Koblenz or Cologne), these bridges were of almost no use in peacetime and thus were never rebuild after their destruction during the last months of World War 2 (except for the one at Rastatt, which was used to supply units of the French Army stationed in the area).

Tributaries

Tributaries from source to mouth:

Left Thur Töss Aare (Aar) Birs Birsig Ill (France) Moder Lauter Nahe Moselle (Mosel) Nette Ahr Erft Meuse (Maas) (joins part of the Rhine in the shared delta) Vorderrhein.

Right Hinterrhein Ill (Austria) Schussen Wutach Alb Wiese Elz Kinzig Rench Acher Murg Alb Pfinz Neckar Main Lahn Wied Sieg Wupper Düssel Ruhr Emscher Lippe Oude IJssel (Issel) Berkel Erin

Distributaries

Former distributaries

order: panning North to South through Western Netherlands

• Utrechtse Vecht (minor channel in Roman times, flowing into former Zuiderzee lagoon)
• Kromme Rijn - Oude Rijn (main channel in Roman times, dammed in 12th century AD)
• Hollandse IJssel (formed after Roman times, dammed in 13th century AD)
• Linge (big channel in Roman times, dammed in 14th century AD)
• Biesbosch-area (initiated by 1421-1424 AD storm surges and river floods, by-passed since the digging of Nieuwe Merwede canal in 1904 AD)

Canals include

order: upstream to downstream

• Rhine-Main-Danube Canal - southeastern Germany
• Grand Canal of Alsace - eastern France
• Rhine-Herne Canal - northwest Germany
  • which is the connection to the Dortmund-Ems Canal and the Mittellandkanal.
• Maas-Waal Canal - eastcentral Netherlands
• Amsterdam-Rhine Canal - central Netherlands
• Scheldt-Rhine Canal - southwest Netherlands

Geologic history

Alpine orogeny

The Rhine flows from the Alps to the North Sea Basin and the geography and geology of its present day watershed has developed since the Alpine Orogeny began.

In southern Europe, the stage was set in the Triassic Period of the Mesozoic Era, with the opening of the Tethys Sea between the Eurasian and African plates, between about 240 MBP and 220 MBP. The present Mediterranean descends from this somewhat larger Tethys sea. At about 180 MBP, in the Jurassic Period, the two plates reversed direction and began to compress the Tethys floor, causing it to be subducted under Eurasia and pushing up the edge of the latter plate in the Alpine Orogeny of the Oligocene and Miocene Periods. Several microplates were caught in the squeeze and rotated or were pushed laterally, generating the individual features of Mediterranean geography: Iberia pushed up the Pyrenees; Italy the Alps, and Anatolia, moving west, the mountains of Greece and the islands. The compression and orogeny continue today, as shown by the ongoing raising of the mountains a small amount each year and the active volcanoes.

In northern Europe, the North Sea Basin had formed during the Triassic and Jurassic period, and continued to be a sediment receiving basin since. In between the zone of Alpine Orogeny and North Sea Basin subsidence, remained highlands resulting from an earlier orogeny ( Variscan), such as the Ardennes, Eifel, and Vosges.

From the Eocene onwards, the ongoing Alpine Orogeny caused a N-S rift system to develop in this zone. The main elements of this rift are the Upper Rhine Graben in southeast Germany/eastern France and the Lower Rhine Embayment in northwest Germany/southeast Netherlands. By the time of the Miocene, a river system had developed in the Upper Rhine Graben, that continued northward and is considered the first Rhine river. At that time it did not yet carry discharge from the Alps: instead the watersheds of Rhone and Danube drained the northern flanks of the Alps.

Stream capture

The watershed of the Rhine reaches into the Alps today, but it did not start out that way (Berendsen & Stouthamer, 2001; Fig. 2.2 ). In the Miocene period, the watershed of the Rhine reached south only to the Eifel and Westerwald hills, about 450 km north of the Alps. The Rhine then had the Sieg as a tributary, but not yet the Mosel. The northern Alps were drained by the Danube then.

Through stream capture, the Rhine extended its watershed southward. By the Pliocene period, the Rhine had captured streams down to the Vosges mountains, including the Mosel, the Main, and the Neckar. The northern Alps were drained by the Rhône then. By the early Pleistocene period, the Rhine had captured most of its current Alpine watershed from the Rhône, including the Aare. Since that time, the Rhine has added the watershed above Lake Constance ( Vorderrhein, Hinterrhein, Alpenrhein; captured from the Rhône), the upper reaches of the Main (beyond Schweinfurt), and the Vosges mountains (captured from the Meuse) to its watershed.

Ice Ages

The Pleistocene (~2.5 million years ago - 11,600 years ago) was the geological period of the Ice Ages. Since approximately 600,000 years ago six major Ice Ages have occurred, in which sea level dropped 120 m, and much of the continental margins became exposed. In the Early Pleistocene, the Rhine followed a course to the northwest, through the present North Sea. During the so-called Anglian glaciation (~450,000 yr BP, marine oxygen isotope stage 12) the northern part of the present North Sea was blocked by the ice, and a large lake developed that overflowed through the English Channel. This caused the Rhine's course to be diverted through the English Channel. Since then, during glacial times, the river mouth was located offshore Brest (France), and rivers like the Thames and the Seine became tributaries to the Rhine. During interglacials, when sea level rose to approximately the present level, the Rhine built deltas in what is now the Netherlands.

The last Ice Age ran from (~74,000 BP = Before Present) until the end of the Pleistocene (~11,600 BP). In northwest Europe, it saw two very cold phases, peaking around 70,000 BP and around 29,000-24,000 BP. The last phase slightly predates the global last ice age maximum ( Last Glacial Maximum). During this time the lower Rhine flowed roughly west through the Netherlands and extended to the southwest, through the English Channel, and finally to the Atlantic Ocean. The English and Irish Channels, and most of the North Sea were dry land, mainly because sea level was approximately 120 m lower than today.

Most of the Rhine's current course was not under the ice during the last Ice Age, although its source must then have been a glacier. A tundra with Ice Age flora and fauna stretched across middle Europe from Asia to the Atlantic Ocean. Such was the case during the Last Glacial Maximum, ca. 22,000-14,000 yr BP, when ice-sheets covered Scandinavia and the Baltic, Scotland and the Alps, but left the space between as open tundra. The loess, or wind-blown dust over that tundra settled in and around the Rhine Valley, contributing to its current agricultural usefulness.

End of the Last Ice Age

As northwest Europe slowly began to warm up from 22,000 years ago onward, frozen subsoil began to thaw, expanded alpine glaciers began to thaw, and fall-winter snow covers melted in spring. Much of the discharge was routed to the Rhine and its downstream extension (e.g. Menot et al. 2006, Science). Rapid warming and change of vegetation to open forest began about 13,000 BP. By 9000 BP, Europe was fully forested.

With globally shrinking ice-cover, ocean water levels rose and the English Channel and North Sea re-inundated. Meltwater adding to the ocean and land subsidence drowned the former coasts of Europe ( transgression). About 11000 yr ago, the Rhine estuary was in the Dover Strait. There remained some dry land in the southern North Sea, connecting mainland Europe to Britain. About 9000 yr ago, that last divide was overtopped / dissected. These events were well within the residence of man.

Since 7500 yr ago, a situation with tides and currents very similar to present has existed. Rates of sea-level rise had dropped so far that natural sedimentation by the Rhine and coastal processes together could compensate the transgression by the sea: in the last 7000 year the coast line was roughly at the same location. In the southern North Sea, due to ongoing tectonic subsidence, the sea-level is still rising, at the rate of about 1-3 cm per century (1 meter in last 3000 years).

About 7000-5000 BP a general warming encouraged migration up the Danube and down the Rhine by peoples to the east, perhaps encouraged by the sudden massive expansion of the Black Sea as the Mediterranean burst into it through the Bosphorus about 7500 BP.

Holocene delta

At the begin of the Holocene (~11,700 years ago) the Rhine occupied its Late-Glacial valley. As a meandering river, it reworked its ice-age braidplain. As sea-level continued to rise, in the Netherlands the formation of the Holocene Rhine-Meuse delta began (~8,000 years ago). Coeval absolute sea-level rise and tectonic subsidence have strongly influenced delta evolution. Other factors of importance to the shape of the delta are local tectonic activity of Peel Boundary Fault, the substrate and geomorphology as inherited from the Last Glacial, and coastal-marine dynamics such as barrier and tidal inlet formation (Cohen et al., 2002).

Since ~3000 yr BP (= years Before Present) human impact is seen in the delta. As a result of increasing land clearance (Bronze Age agriculture) in the upland areas (central Germany), the sediment load of the Rhine River has strongly increased (Hoffmann et al. 2007) and delta growth has sped up (Gouw & Erkens, 2007). This caused increased flooding and sedimentation, and ended peat formation in the delta. The shifting of river channels to new locations on the floodplain (termed avulsion) was the main process distributing sediment across the subrecent delta. Over the past 6000 years, approximately 80 avulsions have occurred (documented by Berendsen & Stouthamer, 2001). Direct human impact in the delta started with peat mining for salt and fuel from Roman times onward. This was followed by embankment of the major distributaries and damming of minor distributaries which took place in the 11-13th century AD. Thereafter, canals were dug, bends were short cut and groynes were built to prevent the river's channels from migrating or silting up.

At present, the branches Waal and Nederrijn-Lek discharge to the North Sea through the former Meuse estuary near Rotterdam. The river IJssel branch flows to the north and enters the IJssel Lake (formerly the Zuiderzee brackish lagoon, since 1932 a freshwater lake). The discharge of the Rhine is divided among three branches: the River Waal (6/9 of total discharge), the River Nederrijn - Lek (2/9 of total discharge) and the River IJssel (1/9 of total discharge). This discharge distribution has been maintained since 1709 by river engineering works (digging of Pannerdens canal) and since the 20th century with the help of weirs in the Nederrijn river.

Prehistory

Palaeolithic

During the Middle Palaeolithic, ca 100,000-30,000 BP (the dates vary a great deal) western Europe, including the Rhine and Danube Valleys, was occupied by Neanderthal Man, to which belonged the Mousterian culture of stone tools. Mousterian sites are not considered intrusive. It is believed that the Neanderthals may have evolved from the preceding Homo erectus in the vicinity of the glaciers, but the question has by no means been settled definitively.

Neanderthal sites are denser to the south, where open forest prevailed and the limestone terrain offered more caves as dwelling. The Rhine ran through an open tundra, where Neanderthals hunted big game, such as the rhinoceros and the woolly mammoth. Accordingly, open air Mousterian sites have been discovered in and around the Rhine valley.

Mesolithic

Before about 5600 BC, the Rhine Valley, along with most of Europe, was occupied by Cro-magnon man in the Mesolithic stage of cultural development; that is, they hunted and gathered, but owned a larger and more specialized tool kit than the Palaeolithic people, knew more about the plants and animals, and even may have kept a few animals.

Iron Age

During the early Iron Age, both banks of the Rhine were inhabited by Celtic tribes. However, in the beginning of the Pre-Roman Iron Age, ca 600 BC, the Proto-Germanic tribes crossed the Weser River and the Aller River, and expanded the whole distance to the banks of the Rhine. This expansion is shown archaeologically in the form of the Jastorf culture. From ca 500 BC and onwards, the lower Rhine and not the Weser and the Aller would increasingly mark the border between the Celtic tribes and the Germanic tribes.

Historic and military relevance

The human history of the Rhine begins with the writers of the late Roman Republic and early Roman Empire. Nearly all the classical sources mention the Rhine, and the name is always the same: Rhenus in Latin, Greek Rhenos. The Romans viewed the Rhine as the outermost border of civilization and reason, beyond which were mythical creatures and the wild Germanic tribesmen, not far themselves from being beasts of the wilderness they inhabited. As it was a wilderness, the Romans were eager to explore it. This view is typified by Res Gestae Divi Augusti, a long public inscription of Augustus in which he (or his ghost writer) boasts of his exploits, including sending an expeditionary fleet north of the Rheinmouth to Old Saxony and Jutland, which he claims no Roman had ever done.

Throughout the long history of Rome, the Rhine was considered the border between Gaul or the Celts and the Germanic peoples, although it should be noted that the historical ethnonyms do not carry their modern ethno-linguistic definitions. Typical of this point of view is a quote from Maurus Servius Honoratus, Commentary on the Aeneid of Vergil (On Book 8 Line 727):

"(Rhenus) fluvius Galliae, qui Germanos a Gallia dividit"

"(The Rhein is a) river of Gaul, which divides the Germanic people from Gaul."

The Rhine in the earlier sources was always a Gallic river.

As the Roman Empire grew, the Romans found it necessary to station troops along the Rhine. They kept two army groups there (exercitus), the inferior, or "lower", and the superior, or "upper", which is the first distinction between upper Germania and lower Germania. It originally probably only meant upstream and downstream, the Niederrhein and Oberrhein regions of the map included with this article.

The Romans kept eight legions in five bases along the Rhine. The actual number of legions present at any base or in all depended on whether a state or threat of war existed. Between about 14 AD and 180 AD the assignment of legions was as follows. For the army of Germania Inferior, two legions at Vetera ( Xanten): I Germanica and XX Valeria ( Pannonian troops); two legions at oppidum Ubiorum ("town of the Ubii"), which was renamed to Colonia Agrippina, descending to Cologne. The legions were V Alaudae, a Celtic legion recruited from Gallia Transalpina, and XXI, possibly a Galatian legion from the other side of the empire.

For the army of Germania superior, one legion, II Augusta, at Argentoratum ( Strasbourg), and one, XIII Gemina, at Vindonissa ( Windisch). Vespasian had commanded II Augusta before his promotion to imperator. In addition were a double legion, XIV and XVI, at Moguntiacum ( Mainz).

The two originally military districts of Germania Inferior and Germania Superior came to influence the surrounding tribes, who later respected the distinction in their alliances and confederations. For example, the upper Germanic peoples combined into the Alemanni. For a time the Rhine ceased to be a border when the Franks crossed the river and occupied Roman-dominated Celtic Gaul as far as Paris.

The first urban settlement on the grounds of what today is the centre of Cologne along the Rhine was Oppidum Ubiorum, which was founded in 38 BC by the Ubii, a Germanic tribe. Cologne became acknowledged as a city by the Romans in 50 AD by the name of Colonia Claudia Ara Agrippinensium. Considerable Roman remains can be found in contemporary Cologne, especially near the wharf area along the Rhine, where a notable discovery of a 1900 year old Roman boat was made on the Rhine banks in late 2007.

Subsequently language changes began to play a major political role. West Germanic dissimilated into Low Saxon, Low Franconian languages and High German languages roughly along the old lines. Perhaps it had been doing so all along. Charlemagne united all the Franks in the Holy Roman Empire, but he did not rule over a people of uniform language. After his death the empire split more or less along language lines, with the Low Franconian being spoken in the Netherlands and the Low Saxon and High German in what became Germany. The Romanized Franks became the French. The Rhine once again became a political border.

The Rhine as border has been and is a mystical and political symbol. German authors and composers have written reams about it. During World War II, it was still considered the sacred border of Germany, and was still a defensive barrier. The Germans fought especially hard to defend it.

The Rhine is closely linked to many important historical events — particularly military ones — as well as myths. For example:

• The Battle of the Teutoburg Forest which finally established the Rhine as the northern frontier of the Roman Empire.

• It was a historic object of frontier trouble between France and Germany. Establishing " natural borders" on the Rhine was a long term goal of French foreign policy since the Middle Ages, though the language border was - and is - far more to the west. French leaders such as Louis XIV and Napoleon Bonaparte tried with varying degrees of success to annex lands west of the Rhine. The Confederation of the Rhine was established by Napoleon as a French satellite state in 1806 and lasted until 1814, during which time it served as a significant source of resources and military manpower for the French Empire. In 1840 the Rhine crisis evolved, because the French prime minister Adolphe Thiers started to talk about the Rhine border. In response, the poem and song Die Wacht am Rhein ("The Watch on the Rhine") was composed at that time, calling for the defense of the western bank of the Rhine against France. During the Franco-Prussian War it rose to the de-facto status of a national anthem in Germany. The song remained popular in World War I and was used in the movie Casablanca

• At the end of World War I the Rheinland was subject to the Treaty of Versailles. This decreed that it would be occupied by the allies until 1935, and after that it would be a demilitarised zone, with the German army forbidden to enter. The Treaty of Versailles in general, and this particular provision, caused much resentment in Germany and are often cited as helping Adolf Hitler's rise to power. The allies left the Rheinland in 1930, and the German army re-occupied it in 1936, which was enormously popular in Germany. Although the allies could probably have prevented the re-occupation, Britain and France were not inclined to do so, a feature of their policy of appeasement of Hitler.

• In World War II it was recognised that the Rhine would present a formidable natural obstacle to the invasion of Germany by the western allies. The Rhine bridge at Arnhem, immortalized in the book and film A Bridge Too Far, was a central focus of the battle for Arnhem during the failed Operation Market Garden of September 1944. The bridges at Nijmegen over the Waal distributary of the Rhine were also an objective of Operation Market Garden. In a separate operation, the Ludendorff Bridge crossing the Rhine at Remagen became famous when U.S. forces were able to capture it intact — much to their own surprise — after the Germans failed to demolish it. This also became the subject of a film, The Bridge at Remagen.

• In November 1986, a terrible disaster happened as fire broke out in a chemical factory near Basel, Switzerland. Chemicals soon made their way into the river and caused pollution problems. About 30 tons of chemicals were discharged into the river. Locals were told to stay indoors, as foul smells were present in the area. The pollutants included chemicals such as: pesticides, mercury and other highly poisonous agricultural chemicals.

• Mainz Cathedral — this more than 1,000-year-old cathedral is seat to the Bishop of Mainz. It holds significant historic value as the seat of the once politically powerful secular prince-archbishop within the Holy Roman Empire. It houses historical funerary monuments and religious artifacts.

• The Nibelungenlied, an epic poem in Middle High German, tells the saga of Siegfried/ Sigurd, who killed a dragon on the Drachenfels (Siebengebirge) ("dragons rock") near Bonn at the Rhine, of the Burgundians and their court at Worms at the Rhine, and Kriemhild's golden treasure which is thrown into the Rhine by Hagen

• Das Rheingold — inspired by the Nibelungenlied, the Rhine is one of the settings for the first opera of Richard Wagner's Ring cycle. The action of the epic opens and ends underneath the Rhine, where three Rheinmaidens swim and protect a hoard of gold.

• The Loreley/Lorelei is a rock on the eastern bank of the Rhine that is associated with several legendary tales, poems and songs. The river spot has a reputation for being a challenge for inexperienced navigators.