Why did General Putnam execute Sam in My Brother Sam Is Dead?
Sam is convicted of being a cattle thief. The punishment for such a crime, as set forth by General Putnam of the Rebel Army, is death.
Ironically, the cattle which Sam is accused of stealing belong to his own family. Some other men from his unit are actually the real thieves, and when Sam, alerted by his younger brother Tim, goes out to see why there are noises coming from the barn, he discovers that four of the family's cows are gone. Sam goes after the culprits, but in the ensuing confusion, he himself is caught and taken in as a cattle thief. At Sam's court-martial, the men who really did the stealing lie and put the blame on Sam. As a result, Sam is sentenced to death.
Although Tim Meeker manages to secure an audience with General Putnam to plead Sam's case, the General is unyielding. The Rebel soldiers are a ragtag bunch, and have been running wild in the town of Redding. Desperate to keep the support of the people, the General wants to show that he can control his troops, so he is extra harsh with them. General Putnam
"(is) thinking that he can't win the war if he doesn't keep the people on his side. He's thinking that he can't keep the people on his side if the troops are running amok among the civilian population - raping the women, stealing cattle, burning houses. He is determined to scare the wits out of the troops to keep them in line. And he's thinking that it doesn't matter very much who he executes to do it...He is thinking that in the long run if he executes somebeody, he'll shorten the war and save more lives. It doesn't matter to him very much who he exectues; one man's agony is like another's, one mother's tears are no wetter than anybody else's. And that's why he's going to have Sam shot".
The Court-Martial has found Sam guilty, and General Putnam is not in a position where he can "start letting people off easily". Sam is a casualty of war; he is essentially being used as an example to keep the troops under control (Chapter 13).