And so it was, during a visit to France, that he decided to offer his services to the French government. In December 1799 Napoleon had returned to Paris from his triumphs in Italy, and he immediately began planning an attack on England. It was on the 12th of the same month that Fulton proposed to the French to build a submarine to help them in their war effort. His offer was refused but he built the submarine anyway, named it the Nautilus and successfully tested it in the Seine on 13 June 1800. However, the problem of designing a suitable weapon for his submarine — the same as had put an end to Bushnell’s experiment — led Fulton to concentrate instead on underwater explosive devices.
In 1803 he showed his steam launch to Napoleon; this would, if developed, have given the French a major advantage in launching a cross-Channel invasion. However, the innovative Fulton fell foul of one major obstacle: in military matters Napoleon was at heart a conservative. He had even rejected the first practical breech-loading rifles firing self-contained cartridges offered by Pauly of Paris, preferring to put his faith in the old-fashioned muzzle-loading flintlocks. He would never be prepared to risk sending his army to sea based on unproven schemes by Fulton. Disappointed by the attitude of the French, Fulton did what every self-respecting armament salesman would do, and crossed to the other side.
The British were aware that at sea they had the upper hand, but the margins were slim, for at any moment adverse weather or faulty strategy might allow the French army to debouch onto the beaches of southeast England. In such a scenario the British were none too confident of success; far better to prevent the invasion before it could be launched. By 1804 Napoleon was amassing his ‘Grande Armée’ on the heights above Boulogne, and the French navy was busy building invasion barges. The British tried without success to stop them using conventional tactics and technology, but the coastline was difficult to approach and French defence works were just too strong. They needed an advantage, an edge, and Fulton proposed to give them just that.
Although Fulton later claimed that the British response was lukewarm at best, in fact he was supported by the highest echelons of government, who ensured that considerable resources were put at his disposal. He was given the cover name of ‘Mr Francis’ and some of the Royal Navy’s most enterprising officers were seconded to the enterprise.
Following on from his experiments in France, he designed several novel devices for attacking the invasion barges, which like many unconventional weapons before them were generically dubbed ‘infernal devices’. For the first planned attack on Boulogne in August 1804, Fulton produced ‘5 large coffers, 5 small, and 10 hogsheads’. Happily, a folder exists in the National Maritime Museum containing drawings of his inventions, ironically drafted by a Frenchman, a certain Monsieur Garriguer, who sent them to Monsieur Guillemard, navy engineer at Rochefort.The artist would appear to have had first-hand access to some of Fulton’s devices, which had failed to explode as planned.
These ‘infernal devices’ were packed with ‘incendiary balls’ and the space between them filled with gunpowder. They were to be exploded by means of a clockwork delay fuse which tripped a flintlock action, all contained in a waterproof box. The prewound and cocked fuses were to be activated by withdrawing a pin, and the operators were tasked with returning each pin as proof that the devices had been correctly armed.
It appears that Fulton had designed what, in modern terms, are designated sub-munitions. As the shock from exploding black powder would usually be effective only within a limited radius, the sub-munitions could spread mayhem over a wide area, setting fire to sail and cordage and timber alike. One can only hope that Fulton had tested these devices before sending men into combat to risk their lives with them. One basic drawback would appear to be ensuring that the incendiary balls actually caught fire as they were ejected, and were not simply blown to pieces.
To deliver his ‘infernals’ into the ranks of the French, Fulton conceived a stealth craft, a small catamaran to be sculled by a crew of two, dressed in black and wearing masks (like the current image of a ninja). It is unlikely that Fulton himself designed these, but in trials they proved ‘barely discernable at 25 fathoms (46m) and invisible at 35 (64m) even from halfway up the rigging’. The payload was to be carried on the gratings fore and aft. Since these flimsy craft would be completely incapable, in any tideway, of towing the large coffers and even the hogsheads by the efforts of only two men, their weapons must have been the small copper cylinders. That would leave the large coffers and the hogsheads to be towed into release position by oared cutters, allowing them to drift down, joined together in pairs, under wind and current towards their intended victims.
With such emphasis on stealth, it is disappointing to note that the British attack, when it went in against Boulogne on the night of 2 October 1804, was clearly anticipated by French Rear Admiral Lacrosse. To add to the lack of subtlety, the British sent in no less than four fireships, towed by armed launches. Into the middle of all this, Fulton’s stealth teams paddled their catamarans at a snail’s pace. Despite the considerable efforts expended, the results were disappointing. Only one French pinnace was sunk, her crew of fourteen men being killed in the explosion of a fireship they were boarding. There were no casualties on the British side, so the lifeboats appear to have worked as planned.