From GibMap
Grand Battery, the lowest part of the original Moorish Northern Defence was known during Spanish days as the Curtain of St Bernard. This Northern area provided defences for the Landport entrance, the Water Gate, and the Cooperage. A narrow causeway connected Spain to the land entrance into Gibraltar through Landport Gate. The sea would be lapping the Causeway on one side (what is now the Glacis area) and on the other side by water from the Inundation dug in 1704 under orders of the Prince of Hesse- Damstadt. Many years later the Inundation was enlarged and deep pits were excavated in it, the idea being that that the shooters above King's Lines could shoot at anyone attempting to cross the Causeway.
