The introduction of steam made little difference in naval affairs at first, so far as either strategy or tactics are concerned, although it changed the conditions of naval action in two principal ways and in many minor ones. Ships could now, like the early galleys, be placed in any position the commander pleased, and, unlike galleys, this effort could be sustained a long time, for engines do not tire out like human arms. On the other hand, ships propelled by steam needed to return to port at frequent intervals to obtain coal, and naval powers found it necessary to provide, either by possession or treaty, safe coaling-stations in various parts of the world for the use of their cruising fleets. The first steam war-ships were naturally fitted with side paddle-wheels; but as soon as the screw-propeller came into use the navy was quick to adopt it. “By its use the whole motive power could be protected by being placed below the water-line. It interfered much less than the paddle with the efficiency and handiness of the vessel under sail alone, and it enabled ships to be kept generally under sail. Great importance was attached to this, as the handling of a ship under sail was justly thought an invaluable means of training both officers and men in ready resource, prompt action, and self-reliance.” For this reason masts and sails were retained long after they were admitted to be detrimental to the fighting qualities of battle-ships. Naval reformers had to wait until the last generation of “old salts,” trained on “blue water,” had died off, and their scornful sneers at “tea-kettle” seamanship had been silenced in the only way possible, before they could persuade governments to build or men to serve in the new style of vessels. In truth, the transition from the fighting machinery and methods that prevailed until, say, the bombardment of Acre, in 1840, to those that decided the inferiority of China in her struggles with Japan at the Yalu and elsewhere, was rapid enough to make even a sea-dog dizzy. [Illustration: THE “KEARSARGE” GETTING INTO POSITION TO RAKE THE “ALABAMA” AT THE CLOSE OF THE COMBAT.] Excellent types of the war-steamers, intermediate between the old two- and three-deckers and the sailless “ironclads” that followed, were those two actors in that most glorious sea-fight of the American Civil War—the _Kearsarge_ and _Alabama_.