What was "Reconstruction" as noted in the nonfiction book, The Warmth of Other Suns?

After the Civil War ended, the federal government took over the South in what came to be known as Reconstruction. The federal government sent forces who acted as monitors, almost occupiers, to ensure that black citizens were no longer being treated as slaves. The feds watched closely southern authorities to confirm that rights formerly denied to blacks were now afforded to them as freely as they were to white citizens. Everything was available to blacks – on paper at least – they were free to vote, live anywhere, marry, attend neighborhood schools and enroll in colleges. In the mid-1870s, federal authorities believed that equal rights was a settled matter in the South and recalled their monitoring forces allowing southern authorities to take over.