To avoid the tacks, stick with the facts. For example, wouldn't it be interesting to know more about the predominant Civil War authors before McPherson and understand how they differed from him in their interpretations? When and how did historians begin to be influenced by the Civil Rights era in their accounts of the war? Were Southerners who thought the Bible defended slavery completely wrong, and what is the Biblical view of slavery? Is actually owning property in slaves sinful? What does Scripture say about it?
Are any of these questions even remotely interesting?