Final answer:
The Civil War was fundamentally about preserving the institution of slavery rather than states' rights. The states' rights argument was primarily about maintaining the right to own slaves, and Lincoln's Emancipation Proclamation highlighted the central issue of slavery in the conflict.
Step-by-step explanation:
The question of whether the Civil War was more about states' rights than slavery is complex but ultimately rooted in the struggle to maintain the institution of slavery. It's important to note that while the idea of states' rights was indeed an aspect of the secession debate, the primary right at issue was the right to own slaves. When eleven southern states seceded from the United States following the election of President Abraham Lincoln, it was largely due to the belief that Lincoln would challenge the institution of slavery.
During the Civil War itself, the Southern states claimed to be fighting for states' rights. However, what they were actually seeking to protect was the right to maintain and expand the practice of slavery. Lincoln's Emancipation Proclamation, issued in 1863, brought the issue of slavery to the forefront of the war aims and began the process of transforming the war from one of Union preservation into a battle for the freedom and human rights of enslaved people.
After the Union's victory, the Civil War resolved the ultimate showdown between national and state authority. The power balance significantly shifted toward the national government. The ratification of the Fourteenth and Fifteenth Amendments by former Confederate states, which guaranteed equal protection under the law and voting rights, reinforced federal power and helped to ensure civil rights for all citizens.