When you start wars, yes, the blood is on your hands.
Robert E. Lee didn't start the civil war. To insist that he did is illogical on many levels.
"...could turn against his country and fight to preserve slavery."
The civil war wasn't about slavery. It was about whether individual states or the federal government had the right to decide whether it should be legal or not. It could have been any issue -- the argument was over who was the final authority in determining legality within state borders.
"...go to war against a numerically superior foe who could produce more of the weapons to fight a war, and how brilliant is it to go to war with virtually no navy to speak of?"
And yet the south still managed to put up one hell of a fight. Sometimes, there are things worth going to war over, no matter what the odds.