 The first tranche of serious improvements made by the British after the siege focused on the North Front, where the weight of any future attack was likely to be heaviest. A marshy area in front of the Landport Gate was flooded and turned into what became known as "the Inundation", a pear-shaped body of brackish water blocked with palisades, underwater ditches and other hidden obstacles to prevent passage. This left only two narrow approaches to the town, each guarded by barriers and watched over by cannon loaded with lethal grapeshot. The Devil's Tongue Battery was constructed on the Old Mole to provide enfilading fire across the isthmus. The northern defences around the Grand Battery and the Landport were also strengthened.
