It was along these lines that warships next progressed, until, at the end of the 18th Century, the line-of-battle ships were great unwieldy affairs with three gun decks below, on which were mounted a hundred guns. Earlier ships had been built which had carried even more guns than this, but the guns had been smaller and consequently less effective. For those interested in the details of the development of warships from the time of the introduction of gunpowder down to the beginning of steam I recommend two books—“The Royal Navy,” by W. Laird Clowes, and “Ancient and Modern Ships,” by Sir G. C. V. Holmes. I have the space to describe only the final forms that the larger ships took ere the introduction of steam and steel changed radically the design of all naval ships. [Illustration: THE _MERRIMAC_ _An ironclad built by the Confederates during the American Civil War. This ship proved how superior to wooden ships armoured ships could be. She was armed with a ram with which she sank the_ Cumberland, _and her armour amply protected her from the enemy’s guns._ ] At the end of the 18th Century and the beginning of the 19th the greatest warships were called line-of-battle ships. They were great unwieldy affairs, slow and cumbersome under sail, and were meant only to take the shock of battle when rival fleets met. Their sides were high, and below the main deck were three gun-decks, each carrying many cannon that fired through square ports cut in the sides. Sometimes, if the wind was abeam, as it generally was during an engagement, the lower ports on the side away from the wind could not be opened because the deck was so low that the “list” of the ship would have allowed the water to enter, perhaps in such quantities as to sink her. Gradually, however, this lower deck was raised until all the guns on the “lee” side could be used except in heavy weather. The _Victory_, Nelson’s flagship at the Battle of Trafalgar, was a typical line-of-battle ship, and in the hearts of Britons she occupies much the same place as with Americans the frigate _Constitution_ occupies. These two ships—the one a line-of-battle ship and the other a frigate—are of the two types that, toward the close of the era of sail, were the most important ships of naval powers. They occupied in their day positions similar to those occupied by the battleship and the cruiser of to-day. In describing these two particular vessels, then, I shall be describing not merely two outstanding ships, which, fortunately, are carefully preserved by the countries for which they fought, but shall also be describing the two most important types.