[128] The sudden and extraordinary development of rifled ordnance which now took place had a revolutionary effect not only on naval architecture and gunnery but on land fortification. In ’59 Sir William Armstrong, giving evidence before a committee appointed by the War Secretary, stated that he could attain with a specially constructed gun a range of five miles. The statement made a sensation; for in the presence of such a gun most of the existing defences of our dockyards and depots were almost useless. A Commission on National Defence was formed. It reported that new fortifications were necessary for our principal arsenals, the fleet alone being insufficient for the defence of ports. “The introduction of steam,” stated the report, “may operate to our disadvantage in diminishing to some extent the value of superior seamanship; the practice of firing shells horizontally, and the enormous extent to which the power and accuracy of aim of artillery have been increased, lead to the conclusion that after an action even a victorious fleet would be more seriously crippled and therefore a longer time unfit for service.” Thus the command of the Channel might be temporarily lost. As steam facilitated invasion, the immediate fortification of vital points on the South Coast was considered necessary. In short, faith in the mobile fleet was temporarily abandoned. The recommendations of the Commission were carried out almost in their entirety. In the case of Portsmouth, for instance, the reinforcement of the Hilsea Lines, decided on only two years previously, was suspended in favour of a defence of far greater radius--a circle of forts some of which were designed to prevent an enemy from gaining possession, from the land side, of Portsdown Hill, a ridge less than five miles from the Dockyard and therefore a position from which, with the new artillery, the Dockyard could be bombarded. A similar girdle of defences was given to Plymouth. [129] Commander R. A. E. Scott, R.N. [130] Lloyd and Hadcock. [131] Woodcroft: _Steam Navigation_, 1848. [132] de la Roncière: _La Marine Française_. [133] Woodcroft: _Steam Navigation_. [134] Rigaud: _Early Proposals for Steam Navigation_. [135] Enouf: Papin; _Sa Vie et Son Œuvre_. [136] Quoted in Fincham’s _Naval Architecture_. [137] Mr. Taylor’s evidence to Select Committee, 1824. Quoted in Woodcroft’s _Steam Navigation_.