Answer:
The declaration of independence proclaimed that all men are given unalienable rights to life, liberty, and the pursuit of happiness. Slavery prior to the Civil War was the antithesis to that - the idea that some humans because of their skin color were inherently less human than others. The 13th, 14th, and 15th amendments helped the US get closer to the realization of the Declaration of Independence by fixing that oversight (through ending slavery, installing equal rights through citizenship, and the right to the ballot).
