Most of the measures, as outlined above, refer to the first year of the war; but these five types of vessels, converted merchantmen, sloops, gunboats, double-enders, and ironclads, represent the additions to the sea-going navy during the four years. There was also an immense liver fleet, composed of liver-steamboats, rams, ironclads, tinclads, and mortar-boats, a collection of nondescripts, which under the leadership of able commanders, made the naval operations on the Mississippi as brilliant and successful as any in the war.
In the construction of the new ships-of-war, no attempt was made to reproduce the fine screw-frigates of 1855, as they failed to show their usefulness, except perhaps at Port Royal and at Fort Fisher. The Colorado could not be got over the bar, when Farragut went up to New Orleans, and the Roanoke and Minnesota were helpless at Hampton Roads. In the latter half of the war, however, the Department undertook the construction of a class of vessels of considerable size, but very different in character. These were large, wooden steamers, with fine lines, excessively long and sharp and narrow, of light draft for their size, in which every quality was sacrificed to speed. In some of these the length was as great as eight times the beam. They were to be seagoing cruisers. Their main purpose was to capture the commerce-destroyers; and perhaps, in case of foreign complications,
