The North may have won the war, but they did a horrible job in trying to win the peace. The south had their new form of slavery, which was contained in the "Black Codes"; laws passed throughout the South that laid heavy restrictions on what, who, and where African-Americans could be. President Johnson saw that the only way to get the freedmen as subordinates again was to let the south back in he started signing pardons so fast that they had to assign an office to help him keep up. Johnson didn't interfere with the south and they continued their plantations, with the plantation owners running the south, in essence becoming exactly what they were before the war. It was like it had never happened. When Reconstruction was finished neither the North, South, or Freedmen won the entire peace, but the South won the biggest piece of what they wanted because they got slavery (just without the name), they got an easy pass back into the Union, and things reverted pretty much back to the way they had been before the war.
Though slavery was abolished with the passing of the 13th amendment it still existed in the south in the forms of the Black Codes and the Ku Klux Klan. The 13th amendment was passed by congress, it stated that in the US there would be no slavery. The south didn't like that, their whole social and economical structure was based on a very firm foundation of slavery. The Ku Klux Klan (or KKK) was started as a society where plantation owners could go and complain about the loss of their slaves, the crushing defeat they had suffered, and how horrible the North was in general. The KKK then evolved into one of the first terrorist organizations in the US. They would dress up in white sheets and kidnap, beat, lynch, whip, and try to get rid off the African-American race in the south. The Black Codes themselves were laws that got passed in most states in the south which prohibited blacks from renting land/houses, being employed by