Explain why Northern whites who opposed slavery and Southern whites who supported slavery both believed they were fighting to defend liberty.


While many Northerners were appalled by the South's "peculiar institution" and truly believed that abolition of slavery was an absolute necessity, it should be noted that the righteous arguments espoused by some Northerners were born more of convenience than of a deep-seated need to better the situation of Southern slaves.  By the early to mid-1800's, slavery had largely died out in the North primarily because its practicality had vanished.  Northern cities were more densely situated and had become far more industrialized than those in the South, which remained primarily agricultural. Thin, rocky soil had always made New England farming a less than lucrative venture, so industrialization replaced agriculture and slavery was more or less dying out in the Northeast as the cotton gin was making many Southern planters exponentially richer in the South.  All the same, however, Lincoln issued the Emancipation Proclamation about halfway through the Civil War and shrewdly focused the attention of potential Southern allies like England on slavery by making it seem that the war was in fact being fought for freedom of the enslaved.  Lincoln had once said that his primary objective was to save the Union, whether that meant freeing all the slaves, or none of that slaves.  The Emancipation Proclamation "freed" slaves in the territories in rebellion--so in essence, not a single slave was freed--but it turned the focus of the war to liberty for slaves, which was exactly what the South didn't want. 

When the South said they were fighting for liberty, it was in reference to their way of life (slavery) and states' rights, long a bone of contention between the two sections, going back as far as the Constitutional Convention.  The South had always been in favor of nullification of federal law, and contended that they could not only nullify (ignore) federal laws they disagreed with, they could secede as needed from the Union, that this was a primary advantage to a "democracy" and "freedom".  In fact, the Founding Fathers, as they were creating a nation that would "secure the blessings of liberty" at the Consitutional Convention had been forced to ignore the slavery issue for fear the document would not be ratified. 

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