On March 8th, 1862, the _Merrimac_ attacked this fleet. She drove her iron prow straight through the side of the _Cumberland_. This vessel sank almost immediately, and but few of the men were saved. Then the _Merrimac_ attacked the _Congress_, drove her ashore, and set her on fire with red hot shot. Meanwhile, broadside after broadside had been fired at the _Merrimac_; but the shot bounded harmlessly from her sloping iron sides. Night came on, and before attempting to destroy the other three ships, the black monster waited for the daylight. There was consternation all through the North. How could a stop be made to this fearful work of the _Merrimac_? There was no telling what she might do on the morrow. That same night there steamed into Chesapeake Bay a queer looking little vessel which had been built by a famous mechanic, Captain John Ericsson. She was named the _Monitor_. She had a low, flat deck, pointed at both ends. In the center was a round, revolving turret. The vessel was completely plated over with iron, and in the turret were two enormous guns, larger than any that had ever been used before. [Illustration: CONFEDERATE FLAG.] On the morning of March 9th, when the _Merrimac_ steamed out to finish her work of destruction, a stupendous cannon ball came thundering against her black side. As the turret of the little _Monitor_ swung round, there came another and another,--such a battering as never ship's side had felt before that day. The broadsides returned by the _Merrimac_ fell harmlessly on the flat deck and iron turret of the _Monitor_. This battle lasted for nearly three hours. Neither vessel was injured to any extent. Finally the _Merrimac_ withdrew, leaving the _Monitor_ in possession of the bay. In one respect, this was the most wonderful battle ever fought upon the water. It showed to all the nations of the world that new navies must be built. In one day all the war-ships in the world had become old-fashioned. The days for wooden war vessels were over. Let us now return to Captain Farragut. As I have said, by the 18th of April he had succeeded in taking all his vessels over the bar of the Mississippi. But still greater difficulties were ahead of him. Before he could capture New Orleans, he must pass the two forts, Jackson and St. Philip, on opposite banks of the river. First of all, however, he must break through a barricade which was below the forts. This reached from shore to shore, and was made of old hulks of vessels and cypress logs, fastened together with huge iron chains. [Illustration: MAP OF THE LOWER MISSISSIPPI.] Should the barricade be broken and the forts passed, there was still a Confederate fleet to be overcome. This consisted of fifteen ships, gunboats, and steam rams similar to the _Merrimac_. They were drawn up across the river above the forts. Captain Farragut was not discouraged by any of these things, but began at once to carry out his plans.