[manuscript plan] Siège de Schweidnitz en Silésie fait par les trouppes Imperial es commandées par Mr. le de Nadasti ...

This fine manuscript shows the layout of the city of Swidnica with its surrounding defence wall, its advanced bastions and suburbs, roads and two nearby villages. In lower right part of the river Bystrzyca.
The plan indicates the positions of the Austrian imperial army under the command of Nadasdy sieging the town.
The title in lower left corner also mentions “que “la tranchée fut ouverte le 27 8bre 1757 et la place fut rendue par les Prussiens le 12 9bre de la même année”.

In 1757, at the beginning of the Seven Years' War, Austria tried to take over the rich province of Silesia from Prussia, which was conquered in 1742. The Austrian army succeeded in taking the town of Schweidnitz in December 1757 but lost it the year.

The plan is dated 1769 and signed Ruel de Bellisle lower right. The scale is in “toises”, the relief is marked by shadows. On verso of the plan is the title "Allemagne Siège de Schweidnitz fait par les impériaux en 1757”.

Nicolas-Tbomas de Ruel de Bellisle, was a Captain the Corps of Royal Engineers and member of the Nobility of Normandy (France).

The fortress of Swidnica is located at an important crossroad linking Breslau, Glatz, Landeshut and the axis Bunzelwitz-Striegau-Liegnitz. Frederick II improved the town 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 field works to constitute continuous fortifications.

Franz Leopold von Nádasdy auf Fogaras (1745-1763), was an Austrian General of Cavalry.On September 7, Nádasdy led the successful attack on an isolated Prussian corps in the Combat of Moys. Finally, on November 13 after besieging Schweidnitz for only 16 days, he captured this important fortress. On December 5 at the Battle of Leuthen, Nádasdy led the cavalry of the Austrian left wing. He suffered from biased reports of his conduct during the battle and never assumed command again for the rest of the war.