By 1803 Boulogne had become an enormous camp for a French Army of over 130,000 men and 22,000 landing boats, poised ready to invade Britain. The Royal Navy had also by then begun to blockade French ports to prevent the invasion force leaving French waters. However, some form of coastal defence system for England was needed in the light of French raids in Wales and Ireland, and the experience of Mortella Point gave birth to the Martello Towers.
The idea to erect towers along the English coast at this time was put forward by a Captain W.H. Ford of the Royal Engineers, who proposed a chain of square towers along the Kent and Sussex coast. Ford, however, was not the first to come up with this idea; in 1798, a Captain Reynolds had proposed a line of towers in similar positions to those that were begun seven years later.1 "...there are no Works that appear to me so likely (to prevent an enemy landing) as a Simple Tower of Brickwork defended by a Handful of Resolute Men."2
Indeed, the concept of a brick tower for coastal defence was a standard military engineer's solution which had already been widely used. Reynolds's proposed line of towers ran along the Kent coast, into Sussex and the low beaches of Pett Level and Pevensey Bay to Seaford, but actually extended past Seaford and westward as far as Littlehampton, involving something in the region of an extra forty towers. The threat of invasion from France receded as Napoleon invaded Egypt, and when he once again threatened to cross the Channel, the plan for towers along the coast resurfaced, this time submitted by Captain Ford.
Ford sent his plans to his superior, Brigadier-General Twiss, who was to play a major role in the Martello Tower story. Twiss was impressed by the scheme and was known to see the addition of towers as the solution to any defence work that needed to be bolstered. He passed the proposal on to his superiors, one of whom was General Sir David Dundas, whose guns had bombarded the Mortella Tower. The whole issue caused controversy throughout Parliament and the Armed Forces. The Royal Navy was very enthusiastic for the towers to be built, Admiral Jervis leading support. The Army was divided in its opinion.
The proposal reached the Secretary of State for War, who asked the Committee of Royal Engineers to give their opinion. The members of the Committe were Twiss, Lieutenant-General Robert Morse, the Inspector-General of Fortifications, and Colonel Abraham D'Aubant. The latter pair had inspected round towers on Guernsey sixteen years previously. They favoured towers, but not the square design, and so proceedings were delayed.
The delay might have been greater, but in 1804, William Pitt became Prime Minister. He became interested in coastal defence, possibly influenced by Colonel Sir John Moore, who had been present at the capture of the Mortella Tower. As a result, Twiss was sent to survey the coastline of south-east England from Beachy Head at Eastbourne, to Dover, to determine suitable sites for the towers. On completion of the second survey, September 3rd, 1804, Twiss wrote to Lt-General Morse from Dover:
"My first object was to apply the general Principles of Fortification which the Committee of Royal Engineers had approved to the Defence of this exposed Line of Coast, and it occurred to me that the simple Tower of about 29 feet diameter, arched over and having on its top, one heavy gun and two carronades, would apply throughout, by placing them within five or six hundred yards of each other in the most advantageous Landing Places, and extending their distances as circumstances might render admissible." 3
Twiss went on to describe the sites for fifty-eight towers which he proposed be built between Eastbourne and Folkestone. The area eventually spanned by the south coast Martello Towers is shown in the box on the map on the right.
Twiss's proposal was put before a conference at Rochester, Kent, on October 21, 1804, exactly one year before the Battle of Trafalgar which effectively negated the need for Martello Towers. The proposal that emerged from the conference planned to build eighty-three towers, two eleven-gun towers (known as 'redoubts') at Eastbourne and Rye, and a four-gun tower at Dymchurch, as well as the modernisation of one of Henry VIII's forts, Sandgate Castle at Shorncliffe. Pitt was convinced of the need for towers, much to the disgust of John Brown, whose own project, the Royal Military Canal, was overshadowed by the Martello issue at the conference. The towers were finally to be built.
The number and design details of the towers were altered many times, and the redoubt proposals revised. The towers were eventually designed to be circular and the armament was revised, due to the lack of space on the roof. This meant that the two carronades were not part of the final design, and a standard tower was armed with just the 24-pounder cannon, but Towers 1-9 and nine others in Sussex were also fitted with a 5½-inch howitzer, to supplement the main armament.4 This extra piece of ordnance was first proposed to be fitted to twenty-six towers, then reduced to the nine Kent towers, but was later increased to eighteen. The purpose of the howitzer was for the defence of the tower should a hostile force be able to approach making use of 'dead ground' which could not be fired upon by the 24-pounder.
Other changes to the planned line of defence involved the Circular Redoubts. The redoubt at Rye was cancelled, and instead built at Dymchurch in place of the four-gun tower, and the number of cannon for the redoubts dropped to ten. Prime Minister Pitt later intervened and had the number of Martello Towers increased. Each tower was to be numbered, Tower 1 being in Folkestone and Tower 74 in Seaford.