After the Civil War ended in the 1860's, Republicans in the north began reconstructing the union. The main goals for the north were to bring the southern confederate states back into the union and to somewhat punish them. Goals of the (white) southerners were to keep newly freed blacks from becoming equal with them, because the 13th amendment had just been passed, putting an end to slavery. Finally, goals of the newly freed blacks were mainly focused on equality with white americans. Because of these conflicts in goals, the failure to bring complete equal rights to all newly freed blacks during the reconstruction of the 1860's and 70's was mainly due to the social war between the northern and southern white americans.
When Lincoln was assassinated and Johnson took his place as president in the White House, the Civil Rights Act came into effect. Because it basically said that newly freed blacks in the south were now US citizens, white southerners began using things like black codes to keep segregation between white and black americans.
Johnson vetoed the CRA, so congress passed the 14th amendment.
Among the newly freed blacks in the south were people like Booker T. Washington or WEB DuBois; Washington wanted the blacks to slowly gain education in literacy and complete equality, whereas DuBois wanted immediate action among blacks.
When the Wade-Davis Bill was passed, military troops were put in the south to enforce the 14th and 15th amendments. The recently passed 15th amendment granted newly freed blacks the right to vote. This new "force act" of military enforcement made sure that black codes like poll taxes and literacy tests would not be used. During the time of this force act, the Ku Klux Klan began to work around the law and punish black citizens.
When the military force act was removed from the south, white southerners rose back up and took their place. Black codes were practiced once again, the KKK was stronger than ever, and our nation began 100 years of segregation between black and white citizens. In this, the failure to bring equal rights to blacks during reconstruction was proven.