Seven Years War (1756-1763). Third Silesian War. Map of the Siege of Schweidnitz, 1757. An Austrian army corps under the command of General Franz Leopold von Nadasdy surrounded Schweidinitz on 14 October 1757. On 15 March 1758, Frederick the Great moved to Breslau. Before starting the new campaign, he had to control the still Austrian-held town of Schweidnitz. The order to begin the siege of Schweidnitz was given to General von Tresckow. On 18 April 1758 the Austrian garrison of Schweidnitz abandoned the fortress and laid down their arms. The fortress was occupied by the Prussians under Colonel von Zastrow. Published in 1765 by the cartographer Jean de Beaurain (1696-1771) as an illustration of his Great Map of Germany, with the events that took place during the Seven Years War. Etching and engraving. French edition, 1765. Military Historical Library of Barcelona (Biblioteca Histórico Militar de Barcelona). Catalonia. Spain. Author: Jean de Beaurain (1696-1771). French geographer.