Another change was taking place in the armament of warships and coast defences. The rifled cannon was still in the experimental stage, but explosive shells, which in Nelson's days were only fired from mortars at very short range, had now been adapted to guns mounted on the broadside and the coast battery. Solid shot were still largely used, but the coming of the shell meant that there would be terrible loss in action in the crowded gun-decks, and inventors were already proposing that ships should be armoured to keep these destructive missiles from penetrating their sides. The attack on the sea front of Sebastopol by the allied fleets on 17 October, 1854, was the event that brought home to the minds of even the most conservative the necessity of a great change in warship construction. It rang the knell of the old wooden walls, and led to the introduction of armour-clad navies. The idea of protecting ships from the fire of artillery and musketry by iron plating was an old one, and the wonder is that it did not much earlier receive practical application. The Dutch claim to have been the pioneers of ironclad building more than three hundred years ago. During the famous siege of Antwerp by the Spaniards in 1585 the people of the city built a huge flat-bottomed warship, armoured with heavy iron plates, which they named the "Finis Belli," a boastful expression of the hope that she would end the war. An old print of the "Finis Belli" shows a four-masted ship with a high poop and forecastle, but with a low freeboard amidships. On this lower deck, taking up half the length of the ship, is an armoured citadel, with port-holes for four heavy guns on each side. The roof of the citadel has a high bulwark, loopholed for musketry. On three of the masts there are also crow's-nests or round tops for musketeers. Heavily weighted with her armour, the ship had a deep draught of water, and probably steered badly. In descending the Scheldt to attack the Spaniards she ran aground in a hopeless position under their batteries, and fell into the hands of the Spanish commander, the Duke of Parma. He kept the "Finis Belli" "as a curiosity" till the end of the siege, and then had her dismantled. If she had scored a success, armoured navies would no doubt have made their appearance in the seventeenth century.