1758 - Siege of Schweidnitz

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The siege took place in April 1758

Description of Events

On March 15 1758, Frederick II moved out of Breslau (actual Wrocław) and established his headquarters at Kloster-Grussau near Landeshut (actual Kamienna Góra). Before initiating the new campaign, he had to eliminate the thorn in his side represented by Schweidnitz (actual Swidnica), isolated but in the hands of the Austrians. Frederick then immediately gave the order to start the siege of Schweidnitz which he entrusted to general Treskow.

On March 16, Frederick left Kloster-Grussau. The corps left under the command of Treskow for the siege of Schweidnitz consisted of 18 battalions and 35 squadrons. His artillery depot was at Jauernick and his ammunition park at Sabischdorf.

On March 22, 10,000 men under the command of Tresckow presented themselves to invest the place. They were supported by a train of siege artillery.

The Austrian garrison counted some 8,000 men under the command of count Thürheim. The Austrians were already greatly tried by blockade of Schweidnitz during the last three months of the winter.

On April 1 and 2, under a torrential rain, the first parallel was opened without any intervention of the besieged garrison which did not notice the work until it was finished.

On April 2, the siege operations began.

On April 8, the batteries were ready and started to cannonade the Galgen Fort. While the weather conditions deteriorated, Balbi, the chief engineer, advised Frederick to attempt an assault.

At 2:00 AM on April 16, three battalions of grenadiers launched a surprise attack on the Galgen Fort. Grenadier Battalion 21/27 Diringshofen led the assault, followed by the Grenadier battalions 28/32 Kreytzen and 41/44 Beneckendorff. The small column quickly crossed the no-man's-land and, at the favour of darkness, ran through the outer defences, escalated the ramparts and fell on the garrison and overpowered it without much difficulty. Losses were relatively light due to the success of the surprise attack:

  • Grenadier Battalion 21/27 Diringshofen = 10 killed and 44 wounded
  • Grenadier Battalion 28/32 Kreytzen = 12 killed and 18 wounded
  • Grenadier Battalion 41/44 Beneckendorff = 1 wounded

On April 18, the garrison surrendered. From the 8,000 men garrisoning the fortress at the beginning of the siege, 5,000 fell into the hands of the Prussians.


The fortress of Schweidnitz (actual Swidnica) is located in Silesia, at an important crossroad linking Breslau, Glatz, Landeshut and the axis Bunzelwitz-Striegau-Liegnitz. In the vicinities of the city, to the east of it, ran the Weistritz river with sandy banks and marshes all along its course. The Weistritz river separates Schweidnitz from its suburb of Kletachkau. To the south of the fortifications of the city lays the suburb of Schreibendt and the mill known as the Neue Mühle, on the banks of a tributary of the Weistritz: the Bögen Wasser.

The city of Schweidnitz was a fortified place which Frederick II improved from 1747 to 1756 through continuous series of works. The works were finished just for the outbreak of the Seven Years' War. Outer works were added to the walls dating from previous periods. Some of these outer works were as far as 500 m. from the city walls. The concept was new and revolutionary. It relied on defensive zones taking advantage of the lay of the land in front of the works and creating areas of cross fire. This approach was an innovation compared to Vauban's theory basing the defence on a continuous rampart completely conditioning the dispositions of the outworks. Developed by the same Frederick, this brilliant innovation, often copied in the military architecture of the XVIIIth century, allowed for a more economic use of fortifications without the huge dispersion of manpower and artillery necessary to defend the extensive perimeter of a city, and the vast construction and maintenance expenses.

The Austrians, who eventually became masters of the fortress, did not really grasp the modernity of its structures and linked the outworks with fieldworks to constitute continuous fortifications.

Map of the fortress of Schweidnitz in 1757.
Source: Kriege Friedrichs des Grossen, volume III by the German Grosser Generalstab

The role of stronghold was assumed by a kind of star or zigzag shaped fortification known as a sternschanze, consisting of a small central irregularly shaped pentagon with a three-pointed base facing the town. A small place of arms occupied the inside of this sternschanze with ramps leading to the platform protected by a parapet; a ditch separated the central redoubt from the external star-shaped curtain wall. The base of the curtain wall ran parallel to the walls of the five-pointed central redoubt whose three longer walls were parallel to those of the curtain wall and its two smaller ones ran opposite to its base. The height of the outer curtain wall allowed to fire from the central redoubt. The zigzagged outer curtain wall was fitted with a ditch and a counterscarp, a covert way and a glacis. In the inner angle between two bastions, covered caponnieres with loopholes for enfilade fire crossed the ditch to link the curtain wall to the redoubt. The central redoubt was armed with 15 heavy guns deployed evenly in three batteries placed at the extremity of each point.

Each sternschanze had its own powder magazine, barracks for its garrison and magazines providing for a certain autonomy for these isolated forts. The entrance was located at the base and accessed through a covert way. The parapet of this covert way, the caponnieres and the base of the curtain wall in the ditch were reinforced by palisades and breastworks of fallen trees. A vast network of countermine galleries existed and was later improved by the Austrians after the capture of the fortress.

Around the town of Schweidnitz there were four of these forts and other minor fortifications. Oriented to the south, the Bögen Fort (star-shaped) then, proceeding counter-clockwise, the Wasser Redoubt (an arrow shaped ravelin) oriented to the southeast, followed by the Wasser Fort in the shape of an irregular hexagon oriented to the east. To the north of this latter fort there was a ravelin (arrow shaped), then the Galgen Fort (star-shaped) which constituted the northeast angle of this ring of forts. To the northeast of it, isolated at a certain distance, there was a small arrow shaped redoubt. Oriented to the north, the Kirchen Redoubt (arrow shaped). At the northwest angle of the ring of fortifications, the Jauernicker Fort (star-shaped) reinforced by the Jauernicker Flèche (a ravelin). Then followed, oriented to the west, the Jauernicker Redoute (arrow shaped), the Garten Fort (star-shaped); the interval between the Garten Fort and the Bögen Fort was occupied by the Garten Redoubt (arrow shaped).

The Wasser Redoubt and the Wasser Fort overlooked the Weistritz river flowing to the southeast of Schweidnitz.

Deployement of the Prussians around Schweidnitz from January to April 1758.
Source: Kriege Friedrichs des Grossen, volume III by the German Grosser Generalstab
Courtesy of Tony Flores
Light blue blocks = Position of the blockading force between January 1 and February 21
Dark blue blocks = Position of the Prussian siege corps between March 19 and April 16

Order of Battle

Austrian Order of Battle

Commander-in-chief: count Thürheim

The Austrian garrison counted some 8,000 men but for now we do not have information about the detailed order of battle of this force.

Prussian Order of Battle

Commander-in-chief: von Tresckow

Summary: 18 bns and 35 sqns

The following Prussian grenadier battalions took part to the siege:

  • 2/G-II Nesse
  • G-NG/G-III/G-IV Wangenheim
  • 29/31 Östenreich
  • G-I/G-XI Lossau
  • 38/43 Burgsdorff
  • 47/G-VII Carlowitz
  • 21/27 Diringshofen
  • 28/32 Kreytzen
  • 41/44 Beneckendorff

...along with the infantry regiments:

  • IR13 Itzenplitz
  • IR19 Markgarf Karl (at Schweidnitz from March 31 to April 18)
  • IR20 Bornstedt
  • IR28 Kreytzen
  • IR29 Knobloch
  • IR36 Münchow
  • IR38 Brandes (at Schweidnitz from January 1 to April 16)
  • IR39 vacant (at Schweidnitz from December 8 to 21 1757)
  • IR46 Bülow (at Schweidnitz from March 31 to April 18)
  • IR49 Erbprinz von Hessen-Cassel (at Schweidnitz from March 31 to April 18)


Archenholz, J. W. von, Geschichte des Siebenjahrigen Krieges in Deutschland, Berlin: 1828

Duffy, Christopher, Fire and Stone: The Science of Fortress Warfare (1660-1860), David & Charles, London: 1975

Fiedler, Geschichte des grenadieres Friedrichs des grossen

Grosser Generalstab, Die Kriege Friedrichs des Grossen, Hiller, Berlin, 1830-1913

Jomini, Henri, Traité des grandes opérations militaires, 2ème édition, 2ème partie, Magimel, Paris: 1811, pp. 66-


Carlo Bessolo for the initial version of this article