Final answer:
Conflict over states' rights, centering on the legality of slavery and its expansion, significantly contributed to the sectional discord that led to the Southern states' secession. The Deep South seceded swiftly after Lincoln's election due to fears of slavery's future and a strong belief in the right to secede. This action, amplified by the attack on Fort Sumter, directly led to the outbreak of the Civil War.
Step-by-step explanation:
The concept of states' rights was a central factor contributing to sectional conflicts between the North and the South in the United States during the mid-19th century, ultimately leading to the secession of the southern states. After the election of Abraham Lincoln in 1860, a president who did not secure a single southern vote in the Electoral College, southern states like South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas rapidly organized secession conventions. The principle of states' rights, as declared by southern leaders like Jefferson Davis, was to protect the liberty inherited from the Revolution, which included the right to own property—slavery—and to take that property throughout the country without federal infringement.
The Deep South's early secession, particularly South Carolina's move in December 1860, was fueled by a concern for preserving slavery and white supremacy, as well as the belief in the legal right to secede from the Union. The failure of the federal government to enforce the Fugitive Slave Act, citing states' rights over federal mandate, was a predominant rationale mentioned in the first ordinance of secession.
The formation of the Confederate States of America, led by the seceding southern states, was a move to shield themselves from what was perceived as Republican encroachment upon their states' rights—fundamentally associated with slavery's protection and expansion. The subsequent Civil War was triggered by Confederate forces attacking Fort Sumter, solidifying the sectional conflict into a full-scale war as the question of preserving the Union or allowing secession became a choice of last resort for both the North and South.