What approaches did the radical republicans take in terms of reintegrating the south into the united states after the civil war?

Radical republicans worked for the complete and immediate annihilation of slavery.

Explanation:

Abraham Lincoln had given his reconstruction plan of integrating the southern states in to the Union which was too lenient and radical republicans felt that Lincoln’s plan was biased and favorable to the south. Radical republicans believed that the civil war had started due to thy harsh approach of the southern states and they deserved to be punished for it.  

Radical republics were a segment of republican political party who were aggressive in taking political moves in the country. They supported for the African American enfranchisement, abolition of slavery and federal funding to the confederate states.