While that despatch of the 9th was on the wires, Jackson, D. H. Hill, Ewell, and Winder were engaged with Pope on the Rapidan. General Pope had advanced from the Rappahannock, to hold the enemy in check till the Army of the Potomac could be brought back from the Peninsula. BATTLE OF CEDAR MOUNTAIN. Fertile and fair are the farms of Culpepper, as beautiful as any in the Old Dominion. They are watered by swiftly running streams. Their slopes are verdant and sunny, sheltered by the Blue Ridge from wintry blasts. Beyond the town of Culpepper, towards the south, there is a hillock, called Cedar Mountain, which rises abruptly, and in shape like a sugar-loaf. Near the Mountain is the house of Rev. Mr. Slaughter. Robinson's Creek winds through his farm, south of the Mountain, on its course to the Rapidan. North of the Mountain is the residence of Mrs. Crittenden. The house is shaded by overhanging trees. It stands on the west side of the highway leading from Culpepper to Madison. Standing there and looking towards the Mountain, we see fields of corn and wheat, groves and woods, bordering the field. General Crawford's brigade of Banks's corps, in the advance from Culpepper to the Rapidan, on the 8th of August, encountered Jackson's pickets at the base of the Mountain, upon the farm of Mr. Slaughter. On Saturday morning, the 9th instant, General Williams's division joined Crawford. As the troops approached the farm of Mrs. Crittenden, the base and summit of the Mountain seemingly became volcanic. There was an outburst of flame and smoke, a screaming in the air, and the deep reverberation of the cannonade. Williams's batteries were soon in position, and replied with shot and shells. General Banks arrived. He formed a line of battle, placing Williams's division west of the Madison road, near Mrs. Crittenden's house, and Augur's division east of it, nearer the Mountain. On the right of the line west of the house was Gordon's brigade, next Crawford, Geary, Greene, and Prince.