Why does Harlan Granger haunt the Logans to sell the land to him?

The Logan's land had previously belonged to the Granger family. The Grangers sold it during the Civil War. They, "had sold it during Reconstruction to a Yankee for tax money." The Granger family bought most of their land back except for the land bought by the Logans. The Grangers still have deep anger over how the Civil War turned out for the South and the Logan's land is a reminder of it.