The Dred Scott decision served as an eye-opener to Northerners who believed that slavery was tolerable as long as it stayed in the South. If the decision took away any power Congress once had to regulate slavery in new territories, these once-skeptics reasoned, slavery could quickly expand into much of the western United States. And once slavery expanded into the territories, it could spread quickly into the once-free states. Lincoln addressed this growing fear during a speech in Springfield, Illinois on June 17, 1858:
Put this and that together, and we have another nice little niche, which we may, ere long, see filled with another Supreme Court decision, declaring that the Constitution of the United States does not permit a State to exclude slavery from its limits. . . . We shall lie down pleasantly dreaming that the people of Missouri are on the verge of making their State free, and we shall awake to the reality instead, that the Supreme Court has made Illinois a slave State. 
For many Northerners who had remained silent on the issue, this very real possibility was too scary to ignore. Suddenly many Northerners who had not previously been against the South and against slavery began to realize that if they did not stop slavery now, they might never again have the chance. This growing fear in the North helped further contribute to the Civil War.
Four years after Chief Justice Taney read his infamous Scott v. Sandford decision, parts of the proslavery half of the Union had seceded and the nation was engaged in civil war. Because of the passions it aroused on both sides, Taney's decision certainly accelerated the start of this conflict. Even in 1865, as the long and bloody war drew to a close with the Northern, antislavery side on top, a mere mention of the decision struck a nerve in the Northern Congress. A simple and customary request for a commemorative bust of Taney, to be placed in a hall with busts of all former Supreme Court Chief Justices, was...