Answer:
They would have to implement full racial integration in order to be readmitted to the Union.
Step-by-step explanation:
The South were in support of slavery and their unwillingness to abolish it made them to leave the Union. The North were against slavery and was in support of its abolition.
After a while they changed their and wanted to come back but the Radical Republican gave them some conditions and requirement and the most objectionable was that they would have to implement full racial integration in order to be readmitted to the Union.