Defending the indefensible is the genre of the neo-rebs. "Cruel and unusual" is a provision from the Constitution - something the southerners had renounced. it didn't apply to traitors. Besides, there is nothing unusual about executing guerillas, spies, partisans, bushwackers, and other traitors. Catch them, shoot them, bury them - by the book.
If you are referring to slavery, I need only note (1) that you'll be hard pressed to find me saying so much as a word that suggests it is anything other than sinful, and (2) that you've already forfeited your right to pass moral judgment on it by embracing torture and murder as positive goods.
"Cruel and unusual" is a provision from the Constitution - something the southerners had renounced. it didn't apply to traitors.
Three problems with that:
1. The term "traitor" denotes a very specific crime upon a specified person or group of persons. It is also a crime that, by its very nature, must be affirmatively decided under the law (unlike murder, which must be ascertained under the law but exists as an act of murder regardless). Thus to call somebody a traitor in fact requires a determination in fact of his guilt in the act of treason.
2. Not one single person who was murdered by Milroy ever had the luxury of a formal proceeding of charges against him much less a determination of guilt, which is required under the laws of war and the procedures of the United States Army even if those charges are conducted by a military authority rather than a civil one.
3. Under no law of war and under no procedure of the United States military is death by way of medieval-style torture permitted as a means of execution, and certainly not when simpler means are available.
But go ahead defending the indefensible, Stalin boy. You're only showing your true colors and they are soviet red.