In the 15 years leading up to the Civil War, a wide variety of theories emerged for how the federal government should deal with slavery expanding, or not expanding, into the territories acquired by the United States.
Since the outbreak of the Civil War and continuing to the present day, the role of slavery in splitting America has been hotly debated. One may wonder whether there was merely a correlation between slavery and the Civil War or whether slavery was the cause. Investigating the nuances of the issue of slavery reveals that the Civil War resulted from sectionalism and slavery, which were practically synonymous.
President James Polk, expecting a fast resolution to the Mexican-American War, “requested from Congress in August 1846 a $2 million appropriation for ‘defraying any extraordinary expenses which may be incurred in the intercourse between the United States and foreign nations.'” Daniel Walker Howe, What Hath God Wrought: Transformation of America, 1815-1848, 766 quoting James Polk, Diary, II, 76-77 (Aug. 10, 1846). Shortly after Congress followed this instruction and drafted a bill, David Wilmot of Pennsylvania introduced an amendment to specify that slavery would not be lawful in any territory acquired. See Daniel Walker Howe, What Hath God Wrought: Transformation of America, 1815-1848, 767.