The Mostly True Adventures of Homer P. Figg by Rodman Philbrick
Homer and his older brother Harold are orphans living on their uncle's farm in Maine during the Civil War. Harold is tricked into joining the Union Army and Homer wants to rescue him from military service. Since their uncle is a hard task master both boys would love to run away and have a life of their own. What follows is an adventure in running away, encountering outlaws and other nefarious characters. Fortunately help comes along from a Quaker farmer active in the Underground Railroad and a naiive clergyman who accompanies Homer on his quest to save Harold. The fun of the adventure is Homer's ability to reinvent the truth and tell tales or lies as needed to escape various situations. The book is a very satisfying and humorous read. You also get a first person account of what life was like during the Civil War.