Final answer:
The Civil War was precipitated by the North's opposition to slavery, exemplified by the defiance of the Dred Scott decision and the election of Abraham Lincoln in 1860, which led Southern states to secede and form the Confederate States of America.
Step-by-step explanation:
The outbreak of the Civil War was influenced by a complex series of events and escalating tensions between the North and South, particularly over the issue of slavery. Southerners' fears were heightened by several key factors, including the northern states' defiance of the Dred Scott decision and the emergence of the Republican Party's antislavery platform.
The election of Abraham Lincoln in 1860, a Republican whose party was committed to preventing the expansion of slavery, was viewed by the South as a direct threat to the institution of slavery and their way of life. This fear led to the secession of the southern states and the formation of the Confederate States of America, propelling the nation into the Civil War.