Misconceptions may be natural, might be accidental, might be the result of a misreading.
In the prologue; because Andrew Johnson was the only member from the South which did not leave, the assumption was that he supported the Union.
That was a misconception; he wasn’t pro Union, he was anti-plantocracy.
Many times, when a person, organisation, government, realises the ‘public’ believes something untrue, yet, which can be used to their benefit, they do nothing to dispel, instead, they feed that misconception.
They use the ‘right’ words, they let the public spin it, and profit from that belief.
If they do it right, people will believe, without doubt, what is an untruth, and it will self perpetuate.