THE mostly TRUE ADVENTURES of HOMER P. FIGG, by Rodman Philbrick (The Blue Sky Press, 2009)
Told in the first person, from Homer's point of view (but not a diary).
Homer and Harold Figg--two orphans, living with their mean old uncle, Squinton Leach, who hates everything, thinks people are better when they're gloomy, and keeps the boys in the barn, likes animals. While Homer and Harold are feeding the pigs, Homer decides to take a piece of the stale crust for himself. When Leach sees this, he goes into a fury. Harold stands up for his little brother, and tells Leach that he feeds the hogs better then them.
So Harold gets sold to the Union Army illegally, and is sent off to fight in the Civil War. Homer runs away to find his brother, and on that adventure he faces slave hunters, guardian fail, even more guardian fail, a medicine show full of treachery and deceit, and the War itself!
This is a great book if you want a bit of action combined with history. If Homer was in my school, I'd automatically want him to be my friend--he's someone who gets things done the right way, but sometimes he has no idea where the train will turn...
This was one of my summer reading books, and I'm making a power point about. Great read! I suggest that everyone read it, because it might well become a classic (and in fact it was a Newbery Honor book).