Or were they? What little I know is that most went on to live profitable happy lives. To some extent, that the commanders and politicians were not brought before the Supreme Court for war crimes, traitorism, etc contributes to their heroic mythos in the south to this day, doesn't it? I mean, openly rebelling and waging war against the federal government could be seen as a war crime right?
At Nuremberg the opinion was that it certainly was(granted the Nazi party lied, murdered, and coerced it's way into power)..
Anyway, it just crossed my mind. Thanks!
I think you're confusing what scholars call jus ad bello and jus in bello. The first concerns the right to go to war, and the second concerns proper conduct during war. Rebellion and war against the US is a question of jus ad bello; by and large, war crimes refer to jus in bello. Rebellion and treason are political crimes, rather than war crimes; they are prohibited in the Constitution for the civil government, whereas war crimes are prohibited by agreed-upon martial custom and the enemy's capacity for retaliation.
No one was tried for treason and rebellion (see my answer here for a brief explanation), but as it happens, there were war crimes trials after the war.
The most famous of these trials was that of Henry Wirz, commandant of the infamous Andersonville prison camp. His was explicitly charged by a military tribunal with
"violation of the laws of war, to impair and injure the health and to destroy the lives—by subjecting to torture and great suffering; by confining in unhealthy and unwholesome quarters; by exposing to the inclemency of winter and to the dews and burning sun of summer; by compelling the use of impure water; and by furnishing insufficient and unwholesome food—of large numbers of Federal prisoners."
As black soldiers proliferated through the Union Army in the later half of the war, the agreed-upon program of prisoner exchanges broke down; following US practice from the Revolutionary War, the Confederates refused to recognize former slaves in enemy uniform as anything but runaway slaves, while the US insisted they be treated equally with white soldiers. This ran completely counter to the Confederacy's animating ideology. As a result of this impasse, the PoW camps were forced to hold far more men than they were ever designed to support, leading to mass death from starvation and disease.
Wirz is the most famous Confederate executed for war crimes, but not the only one. Confederate guerrilla Champ Ferguson was legendary for his sadism, and was charged with war crimes by a military tribunal. He was convicted and executed. All told, about a thousand former Confederates were prosecuted, mostly for crimes related to the mistreatment of PoWs.