I honestly didn't think anyone one this site was even vaguely aware of Landmarkism.Landmarkism was a major highly divisive movement in the mid 1800s.
I know it well.
A few of my elderly relatives were members.
When I was a child, my Dad would take us to their services a few times per year
(out of courtesy to his Aunts & Uncles).
I won't go into detail, but they were very very very different.
I'm not criticizing their beliefs, but IMHO, they are not Baptists.
North or South.