I've often felt that the young men who enlisted in the early days of the Confederacy were motivated by an idealistic, overly-romanticized vision of war. While it didn't take long for them to realize their mistake, many of the recruits seemed to have no idea of the logistics and realities of war and battle. Additionally, they didn't seem to understand that the South was woefully unequipped, compared to the North and its industrial riches.
I don't really think the little guys (soldiers) from either side knew what they were getting into. Not even the low rank officers. Wars are always quite different from what you imagine until you see it for real. Southerners were better at horse riding, shooting, thus they were more seasoned compare to ordinary northern recruits. They also had good general. If I am not mistaken, the south was doing quite well early in the war until the north unleash the differences in the power of mass production, population, technology on them.
You're quite right, Vashstampede--both sides were fueled more by idealism than common practical sense. And yes, the south won a number of the first pivotal battles. I suspect that the only ones who had an inkling of the real horror of war were those who came from fabled military families--such as Robert E. Lee. Even the little West Point cadets recruited by the northern army had really no idea of what actual battle was like.