The film would tell the story of the Hatfields and the McCoys, who were in the first wave of settlers in Tug Valley, with the McCoys living on the Kentucky side and the Hatfields on the West Virginia side. The wealthy Hatfields largely fought for the Confederacy, while the McCoys fought with the Union in the Civil War.
The roots of the feud are in the murder of a McCoy in 1865; in 1878 things kicked into gear thanks to a dispute over ownership of a hog. The McCoys lost that dispute, and in 1880 two members of the family killed the man who testified and cost them the dispute. Then there was an affair between a Hatfield and a McCoy and more killings; the peak of the violence was the 1888 New Years Night Massacre, during which Hatfields surrounded the McCoy cabin, fired rifles inside and set the home on fire to drive out Randolph McCoy. He escaped, but his wife and two of his children were killed.