Read this: Southern Baptist Landmarkism sought to reset the ecclesiastical separation which had characterized the old Baptist churches, in an era when inter-denominational union meetings were the order of the day. James Robinson Graves was an influential Baptist of the 19th century and the primary leader of this movement. While some Landmarkers eventually separated from the Southern Baptist Convention, the influence of the movement on the Convention continued into the 20th century. Its influence continues to affect convention policies. In 2005, the Southern Baptist International Mission Board forbade its missionaries to receive alien immersions for baptism.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): Who was an influential Baptist of the 18th century and the primary leader of this movement?
unanswerable