The Prince’s Lines are part of the Northern Defences covering the approaches to Landport Gate. They stand at about 70 feet (21 m) on a natural ledge above the Queen’s Lines, overlooking the landward entrance to Gibraltar, and run from a natural fault called the Orillon to a cliff at the southern end of the isthmus linking Gibraltar with Spain.
The Prince’s Lines were first started in about 1720, steps built to connect them with the adjacent Queen’s Lines. William Green carried out major improvements after 1761, repairing the parapets, scarping the cliff, repairing the banquets and parapets and smoothing the ditches with mortar. To prevent shells and rubble rolling into the Lines from behind, dry rubble walls were constructed to their rear. The glacis in front of the Lines was also cleared of boulders and crevices were infilled to deny enemy soldiers any shelter. A bombproof barracks, magazine and cookhouse were built at the same time. These features still remain.
The Lines saw considerable fighting during the Thirteenth Siege of Gibraltar (1726–27), when they mounted two cannon and several swivel guns which were reported to have caused heavy casualties among the attacking Spanish force. During the Anglo-Spanish War of 1761–63, they mounted two 9-pdrs and five 6-pdrs, and by 1770 they could accommodate up to fifty wall-mounted guns using sockets cut into the eastern end of the parapet’s crest.
The Lines were bombarded again during the Great Siege of Gibraltar (1779–83). On 11 June 1782, a Spanish shell exploded inside the magazine of Princess Anne’s Battery further up the Rock, causing a massive explosion that blew the flank of the battery into the Prince’s Lines, killing fourteen soldiers.
According to Armament Returns the Prince’s Line was armed in 1859 with one 8-inch Howitzer and one 13-inch Mortar . By 1886 the 8-inch Howitzer had been replaced by one 64/32lbs RML gun but the single 3-ins LS Mortar remained in place.
A communication gallery, Prince’s Gallery was cut in 1790 linking the whole level. An engine room was subsequently built off the Prince’s Gallery to power the various Defence Electric Lights along the Lower Defences. For more information on Defence Electric Lights click here.
An Intrenchment Wall was also built between the Prince’s Lines and the path leading to the Lower Union Galleries. There was a dry moat and parapet. During World War 2 pillboxes were built in this dry moat.
There is a large rock overhand towards the northern end of the Prince’s Lines which used to hold a wooden spiral staircase that drops down to the Queen’s Gallery. This staircase has now collapsed but is still there.