I think that most of us would agree with Dale Schlundt’s answer to this question: “Because who in the middle of the twentieth century wanted to admit great grandpa fought for something other than an honorable and admirable ideology.” The motive is understandable. However, the deception comes at a cost. We cannot understand the present if we do not understand the past, and by denying the crime we dishonor the thousands who suffered and died as a result of the despicable institution of slavery. If we want to live up to our own values and learn from the past we must confront the history of the Civil War honestly.
Read Schlundt’s brief article on this subject here: History News Network | Why Are So Many Distraught to Learn that Slavery Was the Cause of the Civil War?