Forty Hills and Jones' Plantation were two in a series of skirmishes that took place along the North Fork of Bayou Pierre, near Port Gibson, on May 3, 1863. I found them listed in my copy of Indiana at Vicksburg. Warren Grabeau in his book Ninety-Eight Days talks in great detail about the fighting that took place along Bayou Pierre, although he does not use the names Forty Hills or Jones' Plantation.