Why was Radical Reconstruction "radical"?

What
made Radicalradical was its extensive use of federal power to achieve its policy goals. Although
the Civil War appeared to have settled the vexed question of the political and legal supremacy
of central government over the states, Radical Reconstruction still envisaged an expansion of
federal power unprecedented in American history.

The attitude of the
radicals was crucial here. They regarded the Southern secessionists as traitors who needed to be
punished. That meant that strong measures would be needed to ensure that the South would never
rise again. As the vast majority of Southern whites were still implacably opposed to civil
rights for the newly-freed slaves, this meant that only concerted action by the federal
government was capable of implementing both the letter and the spirit of the
Fourteenth...