The place was extremely strong, and Gustavus had in his previous campaign twice failed in attempts to capture it.
Since that time the Imperialists had been busy in strengthening the fortification, and all the peasantry for ten miles round had been employed in throwing up earthworks; but its principal defence was in the marsh which surrounded it, and which rendered the construction of approaches by besiegers almost impossible.

Its importance consisted in the fact that from its great strength its garrison dominated the whole district known as the Marc of Brandenburg.

It was the key to Silesia, and guarded the approaches to Pomerania, and its possession was therefore of supreme importance to Gustavus.

The garrison consisted of five thousand Imperialist infantry and twelve troops of horse, the whole commanded by Count Gratz.

The principal approach to the town was guarded by a strong redoubt armed with numerous artillery.
Colonel Munro had advanced his trenches to within a short distance of this redoubt, and had mounted the twelve pieces of cannon to play upon it, but so solid was the masonry of the fort that their fire produced but little visible effect.