Monday, 5th—We started out at 6 o’clock this morning, and by 11 our corps had destroyed twelve miles of railroad. We then left the railroad and marching ten miles, over very fine roads, went into camp near Oliver Station. A force of eight thousand rebels left Oliver this morning for Savannah. They came into the town last night and throwing up earthworks made preparations for a fight, but this morning they concluded that they had better move on, or they would get hurt, and the infantry left without firing a gun. Our cavalry had a little skirmish with them this morning. The Fifteenth Army Corps is on the west side of the Ogeechee river, but in advance of us, and perhaps the rebels were fearful of being cut off from Savannah.