That same night, while the burning _Congress_ yet lighted up the waters of Hampton Roads, a little ship, as strange-looking and as new to marine warfare as the rebel turtleback herself, arrived by sea in tow from New York, and receiving orders to proceed at once to the scene of conflict, stationed herself near the grounded _Minnesota_. This was Ericsson's "cheese-box on a raft," named by him the _Monitor_. The Union officers who had witnessed the day's events with dismay, and were filled with gloomy forebodings for the morrow, while welcoming this providential reinforcement, were by no means reassured. The _Monitor_ was only half the size of her antagonist, and had only two guns to the other's ten. But this very disparity proved an essential advantage. With only ten feet draft to the _Merrimac's_ twenty-two, she not only possessed superior mobility, but might run where the _Merrimac_ could not follow. When, therefore, at eight o'clock on Sunday, March 9, the _Merrimac_ again came into Hampton Roads to complete her victory, Lieutenant John L. Worden, commanding the _Monitor_, steamed boldly out to meet her. Then ensued a three hours' naval conflict which held the breathless attention of the active participants and the spectators on ship and shore, and for many weeks excited the wonderment of the reading world. If the _Monitor's_ solid eleven-inch balls bounded without apparent effect from the sloping roof of the _Merrimac_, so, in turn, the _Merrimac's_ broadsides passed harmlessly over the low deck of the _Monitor_, or rebounded from the round sides of her iron turret. When the unwieldy rebel turtleback, with her slow, awkward movement, tried to ram the pointed raft that carried the cheese-box, the little vessel, obedient to her rudder, easily glided out of the line of direct impact.