Westphalia, Hesse and Lower Saxony Electoral Saxony Brandenburg Silesia East Prussia Pomerania Iberian Peninsula Naval Operations The siege of Pirna (or Investment of Pirna) took place in 1756 as part of the Prussian invasion of Saxony during the Third Silesian War (part of the Seven Years' War).

The Saxons hoped to receive relief from the Austrian army which was across the border in neighbouring Bohemia under Marshal Browne.

Following the Battle of Lobositz the Austrians withdrew, and tried to approach Pirna by a different route but they failed to make contact with the defenders.

Despite a Saxon attempt to escape by crossing the River Elbe, it soon became apparent that their position was hopeless.

[1] Many of them later deserted and fought with the Austrians against the Prussian forces - with whole regiments changing sides at the Battle of Prague.