No single action during the entire war frightened Northern leaders as badly as the one-day sally of the CSS Virginia. The secretary of war was nearly beside himself with fear that the Virginia would sink all vessels in the area, then attack Union vessels on the Potomac River. The secretary of the navy was, naturally, somewhat calmer, indicating that the shore batteries could at least prevent the latter possibility. On the whole, however, one is inclined to agree with the fears of the Union commanders. In the single presence of the CSS Virginia, nearly all the Northern plans could, potentially, be thwarted. Lincoln, typically, was more intrigued than dismayed. How had the South chanced upon this new possibility, he asked? And what did the Union Navy intend to do about it?