At the end of the Great Siege in 1783, the defeated Commander of the French and Spanish troops, the Duc de Crillon, on being shown the fortifications that had led to the defeat of his troops commented, "These works are worthy of the Romans". This comment highlights the ingenuity of those men who, against all odds endured the onslaught of the advancing forces and were still able to devise a unique system of defense which afforded them victory.

It was during the war of American Independence, when France and Spain made an all out attempt to recapture the Rock from the British in Gibraltar's 14th Siege, recorded as the Great Siege, which lasted from July 1779 to February 1783. The Governor, General Elliot is said to have offered a reward to anyone who could tell him how to get guns onto a projection from the precipitous northern face of the Rock known as the 'Notch'.

Sergeant Major Ince, a member of the Company of Soldier Artificers, forerunners of the Royal Engineers, suggested that this could be done by tunneling through the Rock. Permission was granted, and Ince started work under the direction of Lieutenant J Eveliegh, a Royal Engineer, Aide de Camp to the Governor, on May 25th, 1782.

The tunnellers relied on the strength of their arms, on their skills with a sledgehammer and a crowbar, and were also aided with gunpowder for blasting. In five weeks 18 men had driven a tunnel 2.4sq m by 25m long into the Rock. It is interesting to compare this with the record of a fully mechanized tunneling company in Gibraltar during World War II, who in a week advanced 55m.

Originally there was no intention of mounting guns in this gallery, but as the work progressed the fumes from repeated blasting almost suffocated the miners, so it was decided to open a vent to let air into the tunnel. Almost at once it was realized what an excellent embrasure this would make for a gun, so one was mounted without waiting to reach the 'Notch'.

Other embrasures were cut and guns mounted, and by the time the Siege ended in February 1783, the tunnel was 370 feet (113m) long and had four guns mounted in it. This first gallery was called 'Windsor Gallery'. Sergeant Major Ince did not stop there - he went on to tunnel two other galleries called "King's And Queen's Lines" lower down the north face of the Rock.

Work did not stop with the end of the Siege, but instead of continuing straight towards the 'Notch', a tunnel was driven downwards and a large chamber opened under the 'Notch' called St George's Hall, where a battery of seven guns where installed. The Cornwallis Chamber was also excavated at this time.

In gratitude to Sergeant Major Ince, he was given a Commission and granted a plot of land on the Upper Rock still known as Ince's Farm. In addition, the Duke of Kent (Gibraltar's Royal Governor and father of Queen Victoria) presented him with a valuable horse.

The entrance to the Upper Galleries is dominated by a Victorian 64-pounder cannon. There are other Victorian guns in the Gallery dating back to 1850, as well as an original 18th Century cannon.

The Holy land Tunnel, named as such because the tunnel points due East in the precise direction of Mecca, leads from St George's Hall to the area above Catalan Bay on the East Side of the Rock and affords magnificent views of the Mediterranean Sea. This is just a small part of a network of tunnels inside the Rock of Gibraltar.

During the Second World War, the Royal Engineers (originally the Artificer Company during the Great Siege) added some 40Km of tunnels.

If the Corps of Royal Engineers had not been formed in Gibraltar, there would possibly have been no tunnels excavated.