_La Gloire_, the iron-belted frigate, was the direct result of the lessons gained from the floating batteries in the Russian war. After Kinburn the French naval authorities took up the study of how to apply armour to sea-going ships. Was it possible to embody in a fighting unit sea-going capacity, high speed, great offensive power, in addition to the defensive qualities possessed by the slow, unwieldy batteries? Could such a weight as iron armour would entail be embodied in a ship design without loss of other important qualities? It was concluded that, while it would be impossible to cover the sides completely, it would be possible to protect the surfaces near the water-line, under cover of which all the ships’ vital parts could be secreted. A great increase in defensive power would thus be obtained. Before developing a plan in detail it was decided to carry out further armour trials, and solid iron plates of 4½ inches thickness were fired at with English 68-pounders and French 50-pounders, with solid balls and with charged shells. The results were satisfactory, so these plates were adopted as the standard of armour protection. To the design of M. Dupuy de Lôme the first ironclad frigate was constructed from a fine two-decked ship, the _Napoleon_, which was cut down, lengthened, and armoured from stem to stern. The result was the celebrated _Gloire_. She was followed shortly afterwards by two sister vessels. And then, in order to obtain a direct comparison between timber-built and iron ships, an armoured _iron_ frigate, the _Couronne_, was also built. The three wooden ships were given a complete belt round the water-line of 4½ inches of iron; the _Couronne_ had compound armour--3-inch and 1½-inch iron plates separated from each other and from the iron stem-plating by wood lining 6 inches in thickness. The armament of all four frigates consisted of thirty-six 50-pounder shell guns, carried low. They were given yacht masts and equipped with propelling machinery designed to give them 12 knots speed. §