Who is Harold Figg from The Mostly True Adventures of Homer P. Figg and what is their importance?

Harold Figg is the seventeen-year-old brother of Homer. Harold is sold into the army and forced to take the oath. Harold should be upset about this, especially since the whole thing is illegal, but Harold finds he likes being away from his uncle and his little brother. However, Harold dislikes the sergeant, who is constantly telling him what to do. One day Harold strikes his sergeant and is quickly arrested for mutiny. This appears to be a show of cowardice, but Harold shows his strength and courage when he fights alongside Colonel Chamberlain on Little Round Top at Gettysburg.