To use polite words, the title is disingenuous and disinformative in nature. It is people of the neo confederate / neo nazi movement who are in denial about why the Civil War was fought. The U.S. is yet again falling for "Lost Cause" Confederate ideology, which does NOT come from anyone aligned with the Union.
To know why the Civil War was fought read the secession documents from the eleven states which tried to leave the Union.