Siege of Kehl (1796–1797)

The broad Rhine River and its many tributaries prevented easy escape into France.

The Rhine River flows west along the border between the German states and the Swiss Cantons. The 80 mi (130 km) stretch between Rheinfall, by Schaffhausen and Basel, the High Rhine (Hochrhein) cuts through steep hillsides over a gravel bed; in such paces as the former rapids at Laufenburg, it moves in torrents.[8] A few miles north and east of Basel, the terrain flattens. The Rhine makes a wide, northerly turn, in what is called the Rhine knee, and enters the so-called Rhine ditch (Rheingraben), part of a rift valley bordered by the Black Forest on the east and Vosges Mountains on the west. In 1796, the plain on both sides of the river, some 19 mi (31 km) wide, was dotted with villages and farms. At both far edges of the flood plain, especially on the eastern side, the old mountains created dark shadows on the horizon. Tributaries cut through the hilly terrain of the Black Forest, creating deep defiles in the mountains. The tributaries then wind in rivulets through the flood plain to the river.[9]

The Rhine River itself looked different in the 1790s than it does in the twenty-first century; the passage from Basel to Iffezheim was "corrected" (straightened) between 1817 and 1875. Between 1927 and 1975, a canal was constructed to control the water level. In 1790, though, the river was wild and unpredictable, in some places more than four or more times wider than the twenty-first century, even under regular (non-flood) conditions. Its channels wound through marsh and meadow and created islands of trees and vegetation that were periodically submerged by floods. It was crossable at Kehl, by Strasbourg, and at Hüningen, by Basel, where systems of viaducts and causeways made access reliable.[10]

The plethora of states of the Holy Roman Empire was especially dense on the east bank of the Rhine.

In particular, the states involved in late 1796 included, for example, the Breisgau (Habsburg), Offenburg and Rottweil (imperial cities), the princely states of Fürstenberg, Neuenburg, and Hohenzollern, the Duke of Baden, the Duchy of Württemberg, and several dozen ecclesiastic polities. Many of these territories were not contiguous: a village could belong predominantly to one polity, but have a farmstead, a house, or even one or two strips of land that belonged to another polity. The light cream-colored territories are so subdivided they cannot be named.

The German-speaking states on the east bank of the Rhine were part of the vast complex of territories in central Europe called the Holy Roman Empire.[11] The considerable number of territories in the Empire included more than 1,000 entities. Their size and influence varied, from the Kleinstaaten ("little states") that covered no more than a few square miles to large and powerful states. Their governance varied: they included free imperial cities, also of different sizes, such as the powerful Augsburg and the minuscule Weil der Stadt; ecclesiastical territories, also of varying sizes and influence, such as the wealthy Abbey of Reichenau and the powerful Archbishopric of Cologne; and such durable dynastic states as Württemberg. When viewed on a map, the Empire resembled a Flickenteppich ("patchwork carpet"). Some states included non-contiguous pieces: both the Habsburg domains and Hohenzollern Prussia also governed territories outside the Empire structures, such as the Habsburg territories in eastern Europe and northern Italy. There were also territories completely surrounded by France that belonged to Württemberg, the Count of Solm, the archbishopric of Trier, and Hesse-Darmstadt. Among the German-speaking states, the Holy Roman Empire's administrative and legal mechanisms provided a venue to resolve disputes between peasants and landlords, between jurisdictions, and within jurisdictions. Through the organization of Imperial Circles (called Reichskreise), groups of states consolidated resources and promoted regional and organizational interests, including economic cooperation and military protection.[12]

The fortresses at Hüningen and Kehl were both important bridgeheads across the river. At Strasbourg, a once imperial city, and Kehl, the German village across the river from it, the first permanent bridge had been erected in 1338. In 1678, Strasbourg was taken over by France, and the bridge became part of the city's defense system. Louis XIV ordered the construction of the fortress by the famous architect, Sébastien Le Préstre de Vauban (1679–81), resulting in the construction of the star-shaped fortresses and bridgeheads in both locations. The principal fortresses lay on the west side (French side) of the Rhine; the bridgeheads and the smaller fortifications surrounding those lay on the west side; these protected the various bridges, barrages and viaducts connecting the east and west sides of the river.[13]

While Charles and Moreau jockeyed for position on the eastern slope of the Black Forest, Franz Petrasch engaged the French at Bruchsal, where a sturdy bridge allowed for passage across the river. The troops there, under orders of General Marc Amand Élisée Scherb, included the 68th Demi-brigade and two squadrons of the 19th Dragoons, had remained behind after the Battle of Ettlingen to observe the garrisons of Mannheim and Philipsburg, and to defend passage into France. An initial attack on the French positioned resulted in favor of the French, who charged the Austrians with bayonet, and pushed Petrasch's troops back. Realizing that his command was too small to withstand a concerted attack by the stronger Austrians, Scherb began a withdrawal. On 5–6 September, the Austrians and French spent most of the day skirmishing in advanced posts (Austrian) and rear guards (French); these skirmishes, though, masked the Austrian intention of approaching Kehl and securing the crossing over the Rhine between the village and Strasbourg. By 15 September, part of Scherb's force arrived in Kehl, after having been continually harassed between there and Bruchsal.[20] Once established in Kehl, this small cadre sought to strengthened the fortifications but the lack of cooperation from villagers and local peasants, and the exhaustion of the troops, prevented enhancements from proceeding with any speed.[21]

The Kehl garrison, under command of Balthazar Alexis Henri Schauenburg consisted only of one battalion of the 24th Demi-brigade and some detachments of the 104th. This was too weak to defend a position of such importance, or to develop additional extensive works. Recognizing Kehl's weakness, General Moreau detached a demi-brigade of infantry and a regiment of cavalry from his army in the Black Forest, with instructions to proceed by forced marches to Kehl, but General Petrasch sent Lieutenant Colonel Aspré, with two battalions, to occupy Renchen and to insure that Moreau's reinforcements did not augment the garrison at Kehl.[21]

Before the break of dawn on 18 September (03:45), three Austrian columns attacked Kehl. The principal column, comprising the Regiment Ferdinand, crossed the Kinzig river above the French position and proceeded toward the dykes of the Rhine above Kehl. This placed them between Scherb and his force, and Kehl. Using the dykes as protection, and guided by some peasants who had been previously employed in strengthening the Kehl defenses, they advanced as far as the horn work on the Upper Rhine and entered a gorge which led them to the outskirts of the village.[22] The second column of the Regiment Ferdinand, under command of Major Busch, proceeded via Sundheim toward Kehl, and obtained possession of the village itself, although not the bridge leading to Strasbourg. The third column, which included three companies of Serbians and a division of hussars, executed a false feint on the left bank of the river. One corps of reserve under command of Colonel Pongratz, approached as far as the French earthworks on the banks of the Rhine to support the columns ahead of him; another, which included a battalion of the 12th Regiment, moved past the hamlet of Neumuhl (48°34′12″N 7°50′38″E) toward Kehl.[23] Quickly, the Austrians possessed all the earthworks of the town, the village itself, and the fortress; their skirmishers reached one side of the abutment of the old palisade bridge and advanced to the other side, crossing the islands formed by branches of the Kinzig and the Rhine. They halted almost under the eyes of the French sentinels; there is some confusion about why they stopped, but apparently they mistook the abutment for the last bridge itself.[22]

The French executed several attempts to retake the bridges. The 68th, under command of general Jean-Baptiste de Bressoles de Sisce, was repulsed three times by the superior Austrian numbers and the murderous fire of case shot from four cannons that lined the principal road. The French cavalry tried to retire into Kehl via the Kinzig bridge, but heavy Austrian fire destroyed most of them. Not until 19:00 did fortune favor the French, when Lieutenant Colonel Aspré and two hundred men of the Regiment Ferdinand were captured within the fort itself. The next in command, Major Delas, was badly wounded, and there remained no one in overall command of the 38th Regiment. The French general, Schauenburg, who had gone to Strasburg for troops, returned with some reinforcements and met at once an impetuous Austrian attack.[24] At 22:00 the Austrians still held the redoubt and the houses at the edge of the village; the arrival of a fresh battalion of the Habsburg Regiment Manfredini led to a new attack, but it was repulsed. The Austrians had insufficient reserves to meet the fresh troops from Strasbourg. By 23:00, the French had recovered the fort, Strasbourg, the village of Kehl and all of the French earthen works.[25]

The Austrian failure to hold Kehl and the Strasbourg crossing in September 1796 gave Moreau some measure of security in his actions in the Black Forest and the southern flood plain of the Rhine. If the Austrians had held the crossing, General Petrasch's entire corps could have fallen upon the French army, at that time debouching through the Black Forest defiles and congregating in Freiburg. With sufficient forces, Petrasch also could have advanced as far as Hüningen and carried its tete de point, which had fewer defenders than Kehl. Not only would this embarrass the French who had, up to that point, maintained a steady and secure retreat westward out of southern Germany, it would trap the French army in Germany between Petrasch and the approaching Archduke Charles. As it was, when Petrasch could not actually effect capture of the crossing, he was forced to remain outside Kehl, holding the approaches to the village.[26] Despite the limited success of Petrarsch's action, it had a broad impact on the movements of the main armies of Moreau and Archduke Charles. By preventing French access to the Kehl/Strasbourg crossing, Petrasch forced Moreau to move south; any retreat into France must happen via the bridges at Hüningen.[27]

After the Battle of Schliengen, though, Moreau had only one avenue of escape, via the smallest Rhine crossing at Hüningen, which he used to move his army back to France. The question remained, however, who would control the crossings after the 1796 campaign. Charles had formulated a plan to circumvent that issue, and to free enough of his troops to send a relief force into northern Italy, where Dagoburt von Wurmser held Mantua against the French. If the French would agree to an armistice, he could take command of the Rhine fortresses; the French would withdraw, and he could send a sizable force to northern Italy to help relieve Mantua. The siege of Mantua was long and costly, and had tied up a significant portion of both the French and Austrian force. The French Directory was willing to give up Mantua in exchange for the Rhine bridgeheads, which they deemed more important for the direct defense of France; Henri Jacques Guillaume Clarke, their envoy sent to negotiate between the Austrians and the French in Italy, could not convince Napoleon Bonaparte to allow the Habsburgs to keep Mantua. Napoleon flatly refused the suggestion, maintaining that Mantua was the keystone to the conquest of Habsburg Italy and to maintaining pressure on the Habsburgs in their capital of Vienna.[28]

Charles advised his brother of the French Directory's offer, but it was flatly refused by the Emperor and the civilian military advisers on the Aulic Council. Charles was instructed to lay siege to the fortresses, to take them, and secure any possible French access to southern Germany via the Rhine. The Aulic Council still believed Austrian forces could relieve Mantua. Consequently, by tying Charles down at the Rhine, besieging the highly defensible Vauban fortresses at the river at Kehl and Hüningen, the Council effectively sealed the fate of Wurmser's troops in Mantua. After it became clear that Charles was locked into place on the Rhine, Moreau moved 14 demi-brigades to Italy, leaving behind modest forces on the French border.[29] Two Austrian columns sent from Vienna failed to reach their beleaguered counterparts in Mantua, which fell on 2 February 1797.[28]

The principal bridge crossing the main part of the river began approximately 400 paces above the point at which the Kinzig river joined the Rhine. On one side of the confluence lay the hamlet of Auenheim; on the other the village of Neumuhl. The fortress stood between the bridge over the Rhine and the Kinzig. It was shaped as a polygon, approximately 400 ft (122 m) in length, and two of its sides faced the Rhine. The main wall was approximately 12 feet (3.7 m) high. Below two bastions, casemates, or fortified gun emplacements of 83 ft (25 m) long and 16 ft (5 m) wide, provided enfilade coverage. Behind these lay two other polygons, close the river, which held the magazines: these were 22 ft (7 m) high, 4 ft (1 m) long and 27 ft (8 m) wide. All walls were thick enough to repel most cannon fire. The inner spaces included a section of barracks that cold hold up to 1500 men; indeed, in an earlier bombardment in the hostilities in September 1796, the barracks, gun emplacements, and walls had withstood a lengthy Austrian barrage. The fortress had stone and mortar ravelins and each bastion had its own hornwork; the hornwork between the Rhine and the Kinzig was approximately 250 ft (76 m) in length. The hornworks themselves were faced with stone and mortar and had their own ravelines, a covered communication ditch, and an earthen glacis.[33]

The village of Kehl stood on one of the hornworks, built along a single long street. At one end lay the Commandant's Bridge, which crosses the "old water", a subsidiary channel approximately 400 ft (122 m) wide, separated from the main channel of the Rhine. Beside the old water, stood the Kehl church, graveyard, and portions of the hornwork, including an earthen dam that followed the shoreline of the river. The fortified wall by the churchyard, capped by a breastwork, had its own moat; the breast work had room for at least four cannons and 150-200 troops. This entire installation, called the churchyard redoubt, approximately 100 yd (91 m) wide, dominated the vicinity.[34]

As the Rhine passed the church, it made a sharp curve; this curve and the water where it and the old water rejoin, created a small island known as the Marlener Island. In dry weather, it was more of a peninsula than an island; the exposed ground was called the Kehler Rheinkopf (Kehl's Rhine head, or bald head). The island was thick with bushes and shrubbery. Beside this lay a larger island, known as the Erlenkopf (Erlen head), which supported a battery of artillery (known as Battery 2). The battery was protected only by posts, or palisades, connected to the mainland by a light wood bridge guarded by infantry. The river by the bridge was approximately 200 yd (183 m) wide, and by the exposed islands were about 100 yd (91 m) wide.[35]

In the other direction, between Kehl and the Schutter, which lay downstream, the fortifications were equally secured. The redoubt there held about 8 cannons and 400 men, and covered the street between the hamlet of Auenheim and Kehl.[36]

Strasbourg and Kehl, both built on land and over the river channels, had lengthy systems of bridges connecting the land works to each other, such as this one, the Vauban barrage. This is a modern view of the bridge.

Realizing that the siege was imminent, the French had destroyed most of the village of Kehl on 26 October, as the Battle of Schliengen concluded and Moreau's army withdrew toward Hüningen. Only the ruined walls of the church and post house remained.[37] The French maintained control of the three main islands surrounding the Kehl crossings: Ilse de Estacade, Ilse de Escargots, and Isle de Ehrlin. Their control of these provided vital positions from which the French established their operations. The islands were connected to Kehl and to each other through a series of flying bridges (pontoon bridges); troops could also be moved by boat if necessary.[38]

On 26 October, Baillet de Latour immediately lay the groundwork for a lengthy siege by ordering the construction of extensive earthworks around the bridgehead. The lines of contravallation (the trenches nearest to the French position) included a series of redoubts connected by trenches. Initially, the French considered these to be purely defensive and they were inclined to ignore the industrious Austrian diggers and focus instead on their own fortifications, which were sketchy and relied upon palisades unprotected by dirt; these could not withstand a vigorous attack until strengthened.[39] After several days of strengthening their outer works by 30 October, several artillery pieces were brought up to augment the outer defense. In addition, released from the main army after the Battle of Schliengen, General Dessaix arrived to command the fortress and augment the garrison with his troops. Subsequently, French reconstruction of the fortress and its defensive lines increased. Several minor sorties against the Austrian lines resulted. On 14 November 1796, Dominique Vandamme, commanding a column of Dessaix's force, directed a small group of skirmishers and hussars to attack the most forward of the Austrian posts. This successful sortie took eighty Austrian prisoners.[40] On 21 November, while the Austrians constructed their trenches on the right bank of the Kinzig, the French planned for a considerable sortie against the lines of contravallation between the Kinzig and the Rhine.[41]

At daybreak on 22 November, 16,000 infantry and 3000–4000 cavalry moved against the combined Austrian and Württemberg positions between the Kinzig and the Rhine. The French infantry departed from the small island of Erlen, in the Rhine, and from the left of the entrenchment camp. The first column forced the first two Imperial redoubts. Another penetrated the earthen works near the center and carried the village of Sundheim and the two redoubts that ran contiguously to the village. Three other redoubts between the two were not carried, though, and the Austrians sallied out of these fortifications and fell upon the French. This action was the principal assault on the Austrian/Imperial line and apparently took the besiegers by surprise. Latour and the archduke personally moved to the gap the French created, pulling six battalions of armed workmen and all the Austrian troops after them.[42]

The French immediately ran into problems. Infantry intended to support the first wave did not arrive in time. The cavalry could not deploy properly, due to the marshy ground and close quarters. After four hours, the entire French sortie party withdrew, taking 700 prisoners, seven pieces of cannon, and two howitzers. The want of horses prevented them from taking another 15 pieces of cannon, which they spiked. According to French accounts, thick fog favored the Imperial action, because it prevented the French from reconnoitering. Furthermore, as Moreau reported later, the humidity on the ground impeded the march of their columns, although it is unclear how the fog impeded only French visual reconnaissance and march but not the Austrian's. Regardless, fighting was heavy. General Moreau himself was wounded in the head and his aide-de-camp Lélée was badly wounded. General Desaix's horse was killed under him, and he received a contusion in his leg, and General Latour's horse was also shot from under him.[43] This action convinced the French that the Austrian and Imperial forces were too numerous and too well-established for them to shake. The French instead focused their efforts on reinforcing their palisades, strengthening batteries, and developing the redoubts and earthen works.[44]

Much of the Kehl fortification was built on old ruins. In particular, the oldest of the bridges, which had been largely destroyed earlier in the century, This was an ancient bridge of piles that had been largely destroyed earlier in the century, but which the French had been reconstructing. Where the old stakes remained, the French rebuilt the bridge; where the stakes were missing, they filled in gaps with pontoon spans resting on boats. By 28 November, the Austrians had constructed enough parallels and batteries to fire upon the oldest of the bridges crossing the river. The bridge was entirely demolished; the French repaired it; the Austrians demolished it again. It lay so directly in the line of fire of one of the batteries that it was an easy target. The French could not keep it intact three days straight and furthermore, its wreckage threatened a pontoon bridge immediately downstream.[37]

The Austrians continued to expand their works and erect new batteries. On 6 December, the Austrians opened fire simultaneously with their batteries, and maintained a day-long salvo. At four in the afternoon, they attacked a French position defended by 300 men. They succeeded in taking it, but the French recovered it with a counter-attacked, taking some prisoners. At the same time, though, the Austrians attacked another work, called the Bonnet de Prétre, where only 20 men were posted. They secured it and afterward connected it to the network of fortifications.[45] This gave Austrian marksmen close access to the bridges, where they could pick off French defenders with musket fire. It also allowed sappers to tunnel under the bridgehead walls and engineers to establish artillery batteries that could fire at closer range to the walls. They built some new trenches on the left of the Schutter stream, by the entrance to the old village of Kehl. Similarly, the French had made several night sorties on the works of the besiegers. In these forays, they would chase the diggers out of the lines, but the Austrian reserves always recovered the works before the French could capture any cannons or destroy the construction. Consequently, every day, the Austrians expanded their works and erected new batteries.[37]

On 9 December, in the night, the Austrians attacked the French advanced posts at the ruins of the old post house and church of the old village of Kehl. The fighting was bitter and short, but the Austrians finally took the post, to be driven out the next morning. In this subsequent attack, at which Archduke Charles was present, the Austrians lost about three hundred men and an officer. They attacked again on the 10 and 11 December, but could not take the posts. The Austrians also launched fire ships to destroy the pontoon bridge, but these were repulsed and destroyed.[46] The Austrians took the Ehrlinrhin, a large island on which several of the French reserve units had been positioned. General Lecourbe removed one of the flying bridges to cut off all hope of a (French) retreat, grabbed a standard and rallied a battalion to advance against the Austrians, repulsing them as far as their trenches. Lecourbe's quick thinking preserved half of the island for the French.[47]

In the following days, the Austrians incorporated the newly acquired territory into their massive lines and batteries. The opened trenches on the left (south) of the Schutter) at the entrance to the old village of Kehl; within the week, the Austrian batteries connected the ruins at Kehl with the left flank of the contravallation, and linked the entire line to one of the Rhine islands, now exposed by receding water. The lines of contravallation, formed of several redoubts, were joined by entrenchments that entirely encircled Kehl and access to the bridges. These began at a dyke near Auenheim, traversed the route to Rastadt and Offenburg, the course of the Kintzig and the Schutter rivers, encircled the village of Sundheim, and finished at the Bonnet de Prétre. The Austrian troops on the island could cover the left flank and the entire besieging army was covered by considerable entrenchments on the Islands in the Kinzig. By the end of the week, the Austrian and Imperial defenses were connected in a grand parallel and a series of batteries in a semicircle around the village.[48] The Austrians took the ruins of the church and the post house by bringing up artillery and bombarding the positions; this allowed them to complete the lines of contravallation.[49]

According to spies and deserters, the Archduke himself had been exhorting and cajoling his troops to lift their spirits, "prepared his troops by harangues and presents," Moreau reported. On 1 January, after a lengthy salvo, 12 Imperial battalions attacked the outer redoubt and the right wing of the French entrenchment, drove the French out, and immediately took possession of the earthen works and six pieces of artillery. French reserves had not been able to traverse the Rhine in sufficient time; boats intended to transport such troops had been damaged by the lengthy cannon fire. The connecting bridges, which had also been damaged, were repaired quickly, but by the time these repairs had been made, the Austrians were deeply entrenched in their new positions and the French could not force them out. Even miners, who had dug under the trenches, were unable to blow up the redoubt.[50]

Strasbourgers assist in the demolition of the Redoubt of Kehl on 9 January 1797. Once the surrender occurred, the French took everything they could move, leaving the Austrians naught but a pile of rubble.

Day-by-day, over time, the Austrians increased pressure on the French, who hampered by the lack of bridges or appropriate transport, could not bring up enough reserves to preserve the lost ground. Boats were stove by fire of the cannon; by the time bridges were repaired and sufficient reserves could be moved, the Austrians were entrenched, and had brought up their artillery. The Austrians continued to advance their earth works, and perfect their batteries.[51]

At 10:00 on 9 January the French general Desaix proposed the evacuation to General Latour and they agreed that the Austrians would enter Kehl the next day, on 10 January (21 Nivôse) at 16:00. The French instantly repaired the bridge, rendered passable by 14:00, which gave them more than 24 hours to evacuate everything of value and to raze everything else. By the time Latour took possession of the fortress, nothing remained of any use: all palisades, ammunition, even the carriages of the bombs and howitzers, had been evacuated. The French ensured that nothing remained behind that could be used by the Austrian/Imperial army; even the fortress itself was but earth and ruins. The siege concluded 115 days after its investment, and following 50 days of open (digging) trenches, the point at which active fighting began.[52]

The French garrison consisted of headquarters and three mixed divisions:[55][56]

Louis Desaix led a rearguard action after Emmendingen, and crossed the Rhine north of Kehl. By 24 October, he had moved his forces south to assume command of the fortress and prepare for siege.

Commanding: General Louis Desaix, relieved by Laurent Gouvion Saint-Cyr

• General of Division Jean Baptiste Eblé
  • Chef de Brigade Jean-Baptiste Lobréau[55] Commander of Artillery
  • General of Brigade Anne Marie François Boisgérard, Commander of Engineers
  • Chef de Bataillon Dédon, Bridges.
• 1st Division: General of Division Jean-Jacques Ambert
  • Brigade: General of Brigade Louis-Nicolas Davout 3rd, 10th, 31st Demi-brigades d'ligne, three battalions each[note 3]
  • Brigade: General of Brigade Charles Mathieu Isidore Decaen, 44th, 62nd Demi-brigades d'ligne, three battalions each
• 2nd Division: General of Division Guillaume Philibert Duhesme
  • Brigade: General of Brigade Jean Marie Rodolph Eickemayer, 68th, 76th Demi-brigades d'ligne, three battalions each
  • Brigade: General of Brigade Claude Lecourbe, 84th Demi-brigade d' ligne, three battalions, 93rd Demi-brigade d'ligne, one battalion
• 3rd Division: General of Division Gilles Joseph Martin Bruneteau (called Saint-Suzanne)
  • Brigade: General of Brigade Joseph Hélie Désiré Perruquet de Montrichard, 97th, 100th Demi-brigade, three battalions each
  • Brigade: General of Brigade Jean Victor Tharreau, 103rd, 106th, 109th Demi-brigades d'ligne, three battalions each

Total: 40 battalions

Moreau noted that out of 40 total battalions, 15 battalions were in daily service on the right bank. Six battalions defended the fortification of Kehl itself, three held the entrenchments, three occupied the Ehrlen islands and three held the island of Kinzig. A reserve of six battalions encamped on the left bank of the Rhine. He also rotated battalions through the trenches so none became so exhausted they could not function. He also had additional forces available from the Army of the Rhine and Moselle.[54]

The Austrian force included Infantry, three columns, and cavalry:[56][57]

• General Baillet-Latour, General of Artillery, commander of the Siege
• Lieutenant Field Marshal Kollowrath, commander of Artillery
• Colonel Szeredai, Director of Engineers