Uncle Jed does not like to be called “sir" and prefers to be called Uncle Jed.
Since he is the “son of a Confederate cavalry officer,” Will is not happy about having to accept charity from his aunt and uncle, especially his uncle. He can’t really warm up to calling him anything familiar.
But he knew he’d never feel comfortable around his uncle… He’d be courteous, and he’d help out all he could to make up for being an extra mouth to feed. But he’d never call him Uncle Jed. Never! (Ch. 2)
Will decides to call his uncle “sir” instead of “Uncle Jed” because it seems more distant and less friendly. He does not want his uncle to think that he approves of the fact that he refused to fight for the South. This does not work out though.
“I’ll show you again, then. And call me ‘Uncle Jed.’ I don’t like to be called ‘sir.’ (Ch. 2)
Well, that is a real bummer! He has been thinking this whole time that he is not going to call him “Uncle Jed,” and then his uncle turns around and tells him to call him that! Will is stubborn though. He is convinced that he will not call him “Uncle Jed!” Of course, this will not last. He gets to know his uncle and gives in.
The war is hard on Will. He was orphaned when his father and brother were killed by Yankees, and since his uncle refuses to fight for the Confederates, he considers him a traitor. He does not understand yet that war is complicated. For him, the grief is still too real. He is in too much pain. It is easier to warm up to his aunt, because she seems impartial.
He needs someone to blame, so he blames his uncle. The issue of what to call him is just something that Will can grasp concretely. By silently and verbally refusing to acknowledge his uncle, he is taking some control at a time when he feels helpless.