[4] An aqueduct ran along the Line Wall, enclosed in its masonry, to the Waterport, where it replenished a reservoir from which water for the galleys was drawn.

The Waterport was where the galleys were built (now Grand Casemates Square), and where they could be anchored alongside the Old Mole that extended from the shore to the north.

It played a key role in the defence of Gibraltar during its Great Siege (1779–1783), providing the platform from which red hot shot was fired at the floating batteries of the Spanish forces.

[7] At that time, the main sea defenses consisted on the North, Montagu, Orange, King's and South bastions, with the line wall curtain connecting these positions.

[8] In 1841 General Sir John Jones assessed the defenses at Gibraltar and made recommendations for improvements that set the pattern for many years.