It was indeed the _Monitor_, which had arrived during the night, just in time to save the rest of the Federal fleet.

She was the first regular ironclad ever built.

She was a turret ship, carrying two very heavy guns, and showing only between two and three feet above the water.
The excitement upon both shores as these adversaries approached each other was intense.

They moved slowly, and not until they were within a hundred yards distance did the _Monitor_ open fire, the _Merrimac_ replying at once.

The fire for a short time was heavy and rapid, the distance between the combatants varying from fifty to two hundred yards.
The _Monitor_ had by far the greatest speed, and was much more easily turned than the Confederate ram, and her guns were very much heavier, and the _Merrimac_, while still keeping up the fight, made toward the mouth of the river.
Suddenly she turned and steamed directly at the _Monitor_, and before the latter could get out of her way struck her on the side; but the ram was bent, and her weak engines were insufficient to propel her with the necessary force.