THE UNION AND CONFEDERATE NAVIES
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spars above the deck but a signal-pole forward and aft. Steam broughtwith it also a new weapon. The ram, which had been the principal engineof naval warfare in the Greek and Eoman galleys, had disappeared in theMiddle Ages when galleys were superseded by sailing ships. The latter,being dependent upon the wind for their motive power and direction, couldnot attack an enemy end-on, and hence the ram became useless. Soon afterthe introduction of steam a few men of inquiring and fertile minds, amongthem Commodore Matthew Perry and Mr. Charles Ellet , a distinguished civilengineer, perceived that the steam-engine placed a ship-of-war in the samesituation as the galleys of the classical period, and that the ram might beemployed on the modern vessel to much greater advantage than in ancienttimes. Presently, the whole system of naval tactics underwent a change, dueto the same cause. The close-hauled line ahead, the order of battle for twohundred years and more, gave place to the direct attack in line abreast. Toutilize the guns in this new order of battle, they must no longer be mountedin broadside, but upon elevated citadels, giving them a wider sweep aroundthe horizon. Meantime the guns had undergone a change, and were becom-ing vastly more powerful. First they were adapted to fire shells, which hadhitherto been confined to mortars; next the calibers were increased, thenrifling was adopted, giving greater range, accuracy, and penetration, andfinally breech-loaders came into use. Following closely upon the improve-ments in guns, came the idea of protecting the sides of vessels with a lightarmor, at first of bar iron or of two-inch plates, developed by experimentafter experiment into masses of solid steel, twenty-two inches in thickness.Last of all came the torpedo, of which a slight and tentative use had beenmade as early as 1776, but which only made its way into successful andgeneral employment in the war of 1861.
There were signs of the dawn of this revolution before 1840, and its culmi-nation was only reached during the war. But the twenty years between 1840and 1860 were those in which the movement was really accomplished. Duringthis period the naval administration had endeavored to follow the changesthat were taking place, but it had not fully caught up with them. It hadbegun by building heavy side-wheelers, first the Mississippi and Missouri andnext the Powhatan and Susquehanna. Efficient as these latter vessels wereconsidered in 1847, when they were begun, and even in 1850, when they werelaunched, them model was promptly dropped when the submarine screw wasintroduced in place of the vulnerable paddle-wheel. The six screw-frigateswere accordingly built in 1855, and they were regarded with admiration
by naval men abroad as well as athome. The Niagara , the largest ofthese, was a ship of 4500 tons. Theother five, the Poanohe , Colorado , Mer-rimac, Minnesota , and Wabash , had atonnage somewhat over 3000. All ofthem were heavily armed, and theyformed, or were supposed to form,