CTLAWYER,
Most white southerners did not own slaves. The average soldier in the Civil War was supporting his state. This was on both sides. The idea of fighting for the country really evolved much later.
1. Just because most white southerners did not own slaves does not mean that they had no opinion on slavery. If you want to know why the 11 southern states seceded from the Union, just read their secession declarations. Enslaved African Americans made up a significant percentage of the southern population, particularly in South Carolina, and non-slaveholding whites feared the impacts of emancipation or a slave revolt.
2. How can you say that the idea of fighting for the country evolved much later when Lincoln’s rationale for the war was preservation of the Federal Union? And yes, most soldiers fought as part of state regiments, but the cohesive Army of the Potomac was formed by July 1861, early in the war, after the need for a large, unified and well trained army became clear following the debacle at Bull Run.