Capturing Gibraltar I

Charles Holloway, the engineer, is amongst the principal officers recorded in the commemorative painting of the Siege of Gibraltar by George Carter.

Chevalier D’Arcon’s ‘floating batteries’ (Unknown 1781)

At the start of the siege in 1779, King Carlos III had asked for ideas on capturing Gibraltar. Of the sixty-nine replies, most were too outlandish to consider seriously. One that came to the fore was presented by Pedro Pablo Abarca de Bolea, the Count of Aranda, who proposed a massive Franco-Spanish invasion of England in order to force the British government to concede to various demands, including Spain taking possession of Gibraltar. This plan was received favourably, but shrank in size and scope after being discussed, amended and agreed with the French, resulting in the invasion attempt that had failed so dismally.

When the sustained bombardment of Gibraltar also failed to bring the garrison to its knees, the other plans were considered once again, and in July 1781 that of the forty-seven-year-old French military engineer, Jean-Claude-Eléonor Le Michaud d’Arçon, was chosen. His suggestion was for a combined attack from land and sea, relying especially on a bombardment from formidable floating gun batteries. There had been few previous attempts to build and use such vessels, and d’Arçon’s planned attack against Gibraltar would be the first to employ elaborately designed and constructed floating batteries as the main thrust of an attack. Warships were effectively floating batteries, because their main purpose was to carry as many cannons as possible to counter enemy warships, but they did not have a great deal of protection against cannonballs fired at them. At close range, solid shot could smash through both sides of a warship, and they were particularly vulnerable to red-hot shot, which might burn right through the bottom of a ship, set it on fire or ignite the gunpowder magazines. They could not withstand prolonged artillery fire from batteries on land and had no chance of making a dent in strongly built masonry defences, such as those on Gibraltar. D’Arçon therefore wanted to create gun batteries that floated on the sea, but had the resilience and firepower of land batteries.

By April 1782 he had been working on his plan for several months and had spent a considerable time surveying the coastline and defences of Gibraltar. From time to time suspicious activity was noticed, as on one occasion when Horsbrugh recorded: ‘At five in the morning the Vanguard and Repulse prames fired each a shot at a small boat they supposed to be sounding or reconnoitring.’ Using such a small boat in the dead of night, d’Arçon avoided being wounded or captured while he took soundings close to Gibraltar, but the surveying was only the beginning, because the major work was in the preparation of the floating batteries, which started in Cadiz and then shifted to Algeciras.

British newspapers also published other details they had learned about d’Arçon:

His plan has been adopted, and requires only 18,000 men. He is now at Algesiras, busy in the construction of boats, which are so formed as not to be overset or burnt. It is supposed that the principal attack will be made by sea, towards the New Mole … and the advanced works, which are daily encreasing, will unite in the general onset, the success of which, if not beyond doubt, appears at least very probable to those who are acquainted with the abilities of the engineer.

The attack on the Rock would be a battle between engineers: d’Arçon and his staff, who were devising novel methods of assault, pitted against William Green and his engineers, who were doing everything they could think of to defend Gibraltar.

News of d’Arçon’s scheme soon reached the garrison, and on 11 April one soldier wrote in his diary:

By letters from Portugal, by a boat this morning, we learn that the enemy are fitting up a number of ships, at Cadiz, intended for floating batteries to come against the walls: it is said they are to be lined with cork and oakum, and rendered shot and shell proof; that the Duke de Crillon is to have the command of the army in camp, and that, as soon as he arrives with the conquering troops from Minorca, the regular siege against this place will commence.

Having suffered so much for nearly three years, the soldier was appalled by the arrogance of the suggestion that, up to now, it had not been a proper siege. ‘In the name of all that is horrible in war,’ he raged, ‘what is meant by a siege, if bombarding, cannonading, and blockading on all sides … is not one?’ The idea that the French would now start a ‘regular siege’ probably emanated from their disdain for the Spanish military effort.

D’Arçon’s plan was to convert a number of merchant ships into floating batteries. The work had already begun at Cadiz, where the internal frames of each ship were strengthened and the hull covered with cork and oakum. The unpicked fibres from lengths of old rope were called ‘oakum’, while ‘junk’ was the old rope itself. On Gibraltar, the floating batteries were not only referred to as battering ships, but also as ‘junk ships’ because of the old rope used in their construction. Over this flexible layer of cork and oakum, a complete hull was built of new timber, resulting in a triple-thickness hull designed to absorb the impact of cannonballs, in the same way that worn-out rope made into mats was used by the garrison to absorb the impact of cannonballs fired at their gun batteries. In March one batch of ships had been brought to Algeciras for the next stage of conversion into floating batteries, and more arrived in early May, but Ancell heard that onlookers were not impressed: ‘The eight large ships that arrived over the way the 9th instant [9 May] are hauled close to the shore, and are unrigging, and those that arrived on the 24th March have proceeded to the Orange Grove. It is currently reported that they are lined with cork, and are to be converted into batteries, but most people think that they are more fit for fire-wood, than attacking a fortress.’

This work was taking place within sight of Gibraltar, and the progress of the ships was a subject of constant interest, with Horsbrugh recording what was happening only a few days later: ‘in the Bay of Algaziras they are begun to cut down the quarter deck and poops of the two ships lately hauled in shore, on which work a number of boats and men appear to be employed’. They were being prepared for one or two specially strengthened gun decks within the hull that could support large cannons. Towards the end of May, it became obvious that the ships were also being given additional protection. ‘This forenoon we had a tolerable good view of the Enemy at work on their shipping at Algaziras,’ wrote Horsbrugh. ‘They are covering their larboard [port] sides with timber or planks, which is no doubt intended as a defence against our shot &c.’ Speculation was rife, and another soldier commented: ‘The enemy have been fully employed these ten days past on two very large ships at Algesiras, thickening the larboard side with light materials. They have cut out eleven or twelve ports between decks, and shortened the larboard waist. I suppose they intend to make the upper deck splinter proof, as well as the sides shot proof. From every appearance, they will be snug batteries on the water.’

Because the starboard side was not being reinforced, the assumption was that the floating batteries were intended to fire only from their port side towards the garrison. They would therefore need to be towed into position by boats and be securely anchored, which would make them stationary targets. There was widespread scepticism, and Ancell remarked that ‘most of the garrison are of opinion, from their construction, that they will be found of very little use when they attack our walls, as they never will be able to tow them near enough to do any material execution, for should they daringly come on, their boats will be inevitably cut off by the grape shot from the garrison’.

Progress on the siegeworks slowed down while every effort was concentrated on the floating batteries. The Spanish firing also began to be aimed much more at the garrison’s upper batteries – including Koehler’s guns – that overlooked the isthmus, as Drinkwater saw: ‘The cannonade from the Enemy was now principally directed at our upper batteries. The rock-gun, mounted on the summit of the northern front, was become as warm, if not warmer than any other battery, and scarcely a day passed without some casuals [casualties] at that post.’ Most of the guns at the northern front were positioned on a series of terraces at the western side of the Rock, allowing gun batteries to be ranged in lines to face Spain. On the eastern side of Gibraltar at the north front, the terrain was too steep to establish many gun batteries. Although the sheer cliff face made an assault impossible, the lack of guns able to cover the eastern approach meant that the Spaniards could get very close this way. One legend is constantly repeated about the search for a solution:

the Governor, attended by the Chief Engineer [William Green] and staff made an inspection of the batteries at the north front. Great havoc had been made in some of them by the enemy’s fire, and for the present they were abandoned whilst the artificers were restoring them. Meditating for a few moments over the ruins, he said aloud, ‘I will give a thousand dollars to anyone who can suggest how I am to get a flanking fire upon the enemy’s works.’

At this point, Sergeant Major Henry Ince apparently proposed a tunnel, though there is no evidence that a reward was ever paid or even offered. After discussing such an idea in detail with Colonel Green, Eliott had in fact issued official orders for a tunnel a few days earlier than this supposed conversation, on 1 May: ‘To carry on a cannon communication by means of a souterrain gallery six feet high and 6 feet broad cut thro’ the solid rock beginning … above Farrington’s Battery, proceeding round towards the North East to a very favourable Notche in the Rock, nearly under the Royal Battery, in a commanding situation, being about 640 feet above the Isthmus, and will admit to form a level for a well shouldered establishment of two guns at least.’

The plan was to drive a tunnel eastwards, behind the cliff face, emerging at what they called ‘the Notch’ or ‘the Hook’, a projecting part of the rock face that was topped by an inaccessible platform nearly halfway up the cliff face, which it was hoped would be suitable as a gun emplacement, rather like a bastion, giving a wide field of fire over the area that they were currently unable to reach. It would then be possible, Eliott said in his orders, to respond to ‘any attack or approaches the Enemy may endeavour to push from the Devil’s Tower towards the pass of the Inundation at Lower Forbes, and will flank in an eminent degree any works they may advance towards the outer line … and may also command the access to, as well as the anchorage behind the mountain, all between the north east and south east quarters’.

It took until 25 May to start the tunnel: ‘This morning Sergt. Major Ince of the Artificer Company with 12 miners and labourers begun a new work at Greens Lodge above Willis’s to cut a dreft or subterraneous passage through the Rock to a declivity where a battery is to be made to annoy the enemy.’ Gibraltar nowadays has over 30 miles of tunnels and chambers, but tunnelling had never been attempted before Ince began his work. The mining was done using basic hand tools, with gunpowder for blasting, and the resulting debris was cleared away by hand. It would be a slow process, and time was pressing considering that an assault on the Rock was imminent.

D’Arçon’s plan was that after the floating batteries, gunboats and some warships had battered the garrison into submission, backed up by the gun batteries of the Spanish Lines and the advance works, thousands of troops would invade the Rock in several places, rather than a single massive assault against the strongest defences at the north end of Gibraltar. The attack would be supported by numerous warships of the combined French and Spanish fleet, as well as by every available smaller boat from the locality. Many of the troops were to be transported in small landing craft that had been specially designed by him so that they could attack weaker points in the defences to the south.


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