The defensive walls shown in Bravo’s map were part of the Moorish defensive wall and towers, later reinforced by the Spanish engineers that stretched all the way from the Watergate in the North to the Calita de los Remedios (now Camp Bay). Much of these defences were in a dilapidated state by the time the Anglo-Dutch forces captured Gibraltar. Rosia Bay was soon being used as a safe harbour and a battery was placed on the rocky outcrop above to protect the ships watering in this small cove. The first record of gun emplacements during the British period occurred in 1725 when mention is made of ‘two guns on the mount by Rosia’.
On average, the walls of the battery walls were about thirty-three feet high and some nine feet thick at the rampart with a two-foot parapet. During the Anglo-Spanish War of 1762, these fortifications were heavily armed and included Great Marlborough Battery with three 32-pounders, Fowke’s Battery with three 4-pounders and three 3-pounders, with, on the line, one 32-pounder, three 12-pounders, three 6-pounders and nine 4-pounders. Marlborough Battery had been named in honour of the brilliant career soldier and statesman, John Churchill, First Duke of Marlborough and Fowke’s Battery named after the erstwhile Governor of Gibraltar, Lieutenant-General Thomas Fowke, who served on the Rock from 1754 to 1756.