Historically incorrect or politically/ideologically incorrect?
Sources?
"Far more appalling were the little known executions they committeed on confederate civilians behind enemy lines."
Sources?
So little-known that they are unwritten about in the general literature of the war?
Historically incorrect.
Sources?
One of the more recent books on it is "With Blood and Fire: Life Behind the Union Lines" by Michael R. Bradley. If you desire though I can direct you to the location of the original orders complete with 50+ name murder lists on file at the National Archives.