After the Civil War, liberty was defined as the rights of all men to be treated equally under the law. The US government did their best to ensure that this happened, by implementing the 14th and 15th amendment. These amendments granted citizenship to any person born on US soil, guaranteed equal legal treatment under the Equal protection clause, and allowed black men the right to vote. These were all supposed to be positive steps towards creating a society in which "liberty" meant that all men had the same legal and political rights.
However, this ideal world did not exist after the Civil War. The implementation of Jim Crow laws and "separate but equal" facilities created a society in the South which was based on unequal treatment of African-American citizens.