But, during the transitional period 1860 to 1880, when armour and iron ships, steam engines, rifled guns, and fish torpedoes, were all in their infancy and subject to the most rapid development, no such classification was recognized. The circumstances of the Crimean War, with the adoption of armour and the sudden and enormous growth in the unit of artillery force which took place soon afterwards, led to the first differentiation of ironclads, into ocean-going and coast-defence vessels. We have already noted this fact. We have seen how, especially to the lesser Powers, the turreted monitor appeared to offer an economical and effective form of naval force; and we have noted how, in America, the evolution proceeded in the opposite direction, viz. from coast-defence monitor to ocean-going turret ship. This differentiation prevailed for many years. It prevailed even in the British navy, in spite of its being in full opposition to the offensive principle on which that navy had always based its policy. Later, although convinced that in any war involving this country and its colonies the chief combats must be fought in European waters, naval opinion saw the necessity for a type of ship designed primarily for the defence and attack of commerce: a speedy, lightly armed and protected type capable of overhauling and injuring a weaker, or of escaping from a more powerful enemy. The American War of ’62, in which no general sea action was fought, gave the impulse to the construction of the type which eventually became known as the _cruiser_. Vessels were built in ’63 expressly to overtake Confederate vessels and drive from the seas the Southern mercantile marine. These vessels were to annihilate the enemy’s commerce without being drawn themselves to take part in an engagement, unless in very favourable circumstances. Several such ships were built. The first, the _Idaho_, was a complete failure; the next attempt was little more successful; and those subsequently constructed, the _Wampanoag_ class, the finest ships of the type which existed at the close of the war, which were designed for 17 knots and to carry sixteen 10- or 11-inch smooth-bore cast-iron guns on the broadside and a revolving 60-pounder rifle in the bows, suffered from miscalculations in design and from the weakness peculiar to long and heavily weighted timber-built ships. “These pioneers of the type,” says Brassey, “were followed, both in England and in France, by vessels believed by the builders of their respective countries to be better adapted for the work for which they were designed.”