Siege of Kehl (1733)

Prelude

The village and fortress of Kehl was located near the Margraviate of Baden in the Holy Roman Empire, just across the Rhine River from the French city of Strasbourg. The fortress at Kehl, and that at Philippsburg to the north, provided strategic military control over major crossings of the upper Rhine, which formed the boundary between French-controlled Alsace and the various principalities of the empire.

Nominally the responsibility of the emperor, maintenance and defense of the fortress belonged to the Swabian Circle, which was largely dominated by the Duchy of Württemberg. Although some imperial troops were stationed there in January 1733, the commander of the fortress was the Württembergian lieutenant general Baron Johann August von Phull, and most of its garrison consisted of Swabian troops. When the war broke out, numerous works to repair and expand the fortress were underway, but key defenses near the Rhine were incomplete.

On 12 October, French troops under Belle-Isle and Silly marched into the Duchy of Lorraine and seized its capital, Nancy. Control over the remainder of Lorraine was rapidly established, and the two commanders left garrisons throughout the duchy before sending the bulk of their forces into Alsace to focus on the campaign on the Rhine.

Also on 12 October, Berwick ordered troops from the Strasbourg encampment to cross the Rhine. At a point near Auenheim, about 4 kilometres (2.5 mi) below Kehl, they constructed a ship bridge and crossed 4,000 men to the east bank. Near Goldscheuer, 7 kilometres (4.3 mi) above the fortress, they began constructing another bridge. Two days later, the bulk of the Berwick's army had crossed the Rhine. General Phull, when the French began their movements, destroyed the bridge between Kehl and Strasbourg, and also destroyed those houses and other buildings outside the fortress that might provide the attacking French any sort of shelter.

Siege

Berwick first ordered the construction of a line of circumvallation. Local villagers were among those pressed into service for its construction, which was anchored at both ends by the Rhine, above and below the fortress. Berwick's quartermasters also made demands to the surrounding villages for the delivery of provisions to the besiegers. The Duke of Württemberg signed a supply agreement that he characterized in reports to the emperor as being concluded under the greatest duress.

By 17 October Berwick was ready to begin digging siege lines, and it became apparent to Phull that the fortress' river-facing hornwork was Berwick's target when the latter began construction of batteries on the island between Kehl and Strasbourg. On 18 October Phull issued detailed instructions to his commanders concerning the tactics of defense and retreat. The hornwork was to be held until it was either breached or its artillery rendered useless, at which point the defenders were to fall back first to the covered way between the hornwork and the main fortress, and then to the fortress proper.

The French began digging siege trenches on the night of 19 October. By 21 October the siege lines reached an unfinished lunette on the Rhine-facing side of the fortress, and the French began setting up a battery there on 23 October. The defenders were by this time reduced to musket fire and grenades, as most of their artillery had been dismounted or destroyed by enemy fire.

On 23 October the French opened fire not only on the hornwork, but also began battering the walls of the main fortress with cannon fire. After two failed assaults by Berwick's grenadiers, they succeeded in briefly occupying the hornwork; it was reoccupied by the Germans the next day. The defenders attempted a sortie against the French positions near the hornwork, but it was repulsed. By 27 October, the French had established numerous batteries and were mercilessly battering the main fortification. About 4 pm on 28 October, the French barrage started a fire on the hornwork that was severe enough that its commander requested permission from Phull to withdraw; this permission was granted. Phull then held a council, in which it was determined that only 500 men were combat-ready, and that the fortress might hold out at most three more days. Consequently, Phull raised the white flag around 8 pm on 28 October.

The garrison marched out of the fortress on 31 October with the full honors of war, and was escorted to the imperial defense line at Ettlingen.

Aftermath

The onset of bad weather ended the French campaign for the year, and Berwick, after consolidating his control over the area, quartered his troops for the winter on the French side of the Rhine. In 1734 Berwick continued the campaign down the Rhine, successfully flanking the Imperial defense line at Ettlingen, and continuing with the siege of Philippsburg, during which he was killed by a shell. That siege was successfully concluded by his second in command, the marquis d'Asfeld, and marked the end of significant military operations in the Rhine valley for the war. Pursuant to the 1738 Treaty of Vienna that ended the war, France eventually withdrew from Kehl and Philippsburg, but eventually annexed Lorraine.