Secession and war transformed the immediate issue of the long sectional conflict from the future of slavery to the survival of the Union itself. But two years later, running against a Democratic party split into northern and southern factions, Lincoln won the presidency by carrying every northern state.
And military strength, rather than underpinning a strong, positive, outward-looking central state, gradually evolved into an overly defensive, negative, inward-focussed one.
The United States went to war in to preserve the Union; it emerged from the war in having created a nation. The old decentralized republic in which the federal government had few direct contacts with the average citizen except through the post office became a nation that taxed people directly, created an internal revenue bureau to collect the taxes, drafted men into the Army, increased the powers of federal courts, created a national currency and a national banking system, and confiscated 3 billion dollars of personal property by emancipating the 4 million slaves.
But conflict continued in the arena of historical interpretation and public memory. Northerners including President Buchanan rejected that notion as opposed to the will of the Founding Fatherswho said they were setting up a perpetual union.
On paper, these advantages made the United States much more powerful than the Confederate States.
The first three of these postwar amendments accomplished the most radical and rapid social and political change in American history: the abolition of slavery 13th and the granting of equal citizenship 14th and voting rights 15th to former slaves, all within a period of five years.
Foraging armies devastated rural households and spread animal diseases which returned to devastate herds in the 19th and 20th centuries. Company Aytch by Sam Watkins -- An illuminating Confederate memoir by a Tennessean who fought practically everywhere in the Western theater.