To my knowledge, this only happened at the very beginning of the war, as everyone had their sharp new uniforms on, and people expected neat Napoleonic type warfare, with minimal civilian casualties (and people expected to watch from very far away). It was the common thought at the time that "their" side would win very quickly and easily. Either the rebels would bloody the Northern "wusses" enough right away that they would lose the will to fight, or the Union would stomp out the South due to superior numbers and equipment. So people came to watch their team win, but they were sorely disappointed and quickly this stopped happening.