Before Vicksburg, Saturday, June 20. Awakened this morning by lively reveille from the muzzle of the 9-inch columbiads which opened at 9 A. M., followed by the 30-pound Parrott, then light battery, and a continued crash from all points for six hours, when, at 10 A. M. firing ceased. Whether the stronghold was weakened or not by the process is not known. Our piece alone threw two hundred rounds. The two regiments of infantry were posted in the rear during the fighting. Logan’s men on the enemy’s works digging. Three horses wounded and one negro in the evening from sharp-shooters.