The work begun by Bushnell in 1775 was taken up ten years later by Robert Fulton whose diving-boats so nearly fulfilled the conditions necessary for practical submarine navigation. As America was at peace at this time, and as her financial condition was at the lowest ebb, Fulton transferred his skill and energy to Europe which was then involved in the Napoleonic wars. Several attempts were made to interest the French government in his invention, but although certain commissions reported favorably on his ideas, nothing came of them for a time. In 1800, however, Fulton succeeded in interesting Napoleon in his scheme, and the following year he was given the opportunity of building his first submarine boat, the _Nautilus_. This boat was cigar shaped, about twenty-one feet long and seven feet in diameter, and made of copper supported by iron ribs. When operating at the surface this boat used a peculiarly shaped sail; but when submerged it was propelled by a screw actuated by machinery turned by hand. In this boat, Fulton, with three companions, descended to a depth of twenty-three feet and remained submerged for twenty minutes; and at a depth of five or six feet they are said to have remained submerged for six hours, air being supplied by a copper vessel, probably containing oxygen or compressed air. The first experiment made in attempting actually to destroy a vessel with the _Nautilus_, was successful, a small vessel being sunk. Encouraged by this success Fulton proposed to build larger boats of this same type capable of destroying the largest battle-ships. In return he asked that a reward be paid him for each vessel destroyed, the price of his diving boat reimbursed, and a patent be given himself and the members of his crew, so that in case of capture they would be treated as prisoners of war and not hanged as pirates. Strangely enough this latter clause was the greatest stumbling-block, as the proposed methods of destroying battle-ships by torpedoes was held in such disrepute that the French government would not grant a patent rating the crew of torpedo boats or submarine boats as legitimate belligerents. In effect, their attitude was, that while a person was at liberty to destroy an empire from the surface of the water, he would be hanged as a criminal if he dived beneath the surface and destroyed a boat.