Billy and the Rebel was inspired by a true story of two boys in the Battle of Gettysburg.  From Slave to Soldier is based on the remarkable life of John McCline, a young slave who walked off a Tennessee plantation to join the Union Army.  There are many sites on the Internet for Civil War lesson plans.  Here are just a few:

The Civil War

Gettysburg National Military Park Teacher's Guide

National Archives Black Soldiers in the Civil War

Learning Guide to Gettysburg

LibraryThinkQuest The Battle of Gettysburg