I don't know how this article found its way into the Washington Post rather than say, American Heritage, but here it is:
"But as the internecine conflict lengthened from months to years, and the casualties mounted from the thousands to the hundreds of thousands, the South's desperation spawned a largely untold story: a series of terrorist plots against Washington and New York that eerily foreshadowed September 11, 2001, and its aftermath.
Hatched by politicians, rogue scientists, saboteurs and foot soldiers fanatically loyal to the Confederacy, the plans included spreading yellow fever to Washington and the White House; burning New York City to the ground; poisoning New York's water supply; and attacking Northern ports with a newly developed chemical weapon. There was even a scheme in the war's waning days to blow up the White House, though Lincoln refused to take it seriously. "I cannot bring myself," he said when told of the threat, "to believe that any human being lives who would do me any harm."
While most of the plots failed, their intent was clear. Then as now, they were designed to kill, terrify and demoralize civilians."