This formal drawing deals with tactics rather than the design of a particular project. It shows how a fortress wall may be breached and the bailey within subdued. Four mortars outside the walls rain stones into the fortress, which has long covered galleries with gun emplacements. A section of wall has been undermined and has fallen into the inner ditch. Cannon placed on earthworks either side of the breach direct their fire into the fortress, protected from assault by debris from the collapsed wall.

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