To Colonel Wm. A. Ball, an experienced officer, who had greatly distinguished himself at the battle of Leesburg, and in other encounters, was entrusted by General Lee the duty of holding the town, and in retarding the approach of the enemy, if possible, with the promise of speedy reinforcements. The divisions of Gen. Lafayette McLaws and General Robert Ransom, of General Longstreet's corps, with General Wm. H. F. Lee's brigade of cavalry and a battery of artillery, were marched hurriedly to this point, and the whole of General Lee's army prepared to follow. On Sunday, November 16th, Colonel Ball's scouts announced the approach of the enemy on three roads--the Warrenton, Stafford Courthouse and the Poplar. He telegraphed to General Gustavus W. Smith, in Richmond, for reinforcements. General Smith promptly sent him a battalion of four companies, under Major Finney, from the Forty-second Mississippi. With his small force, which scarcely exceeded five hundred men, the gallant Colonel proposed to engage the enemy, if he sought to cross the Rappahannock near Fredericksburg. Colonel Ball placed his infantry in the mill-race and mill opposite Falmouth, stationed his cavalry in the upper part of Fredericksburg and planted Captain John W. Lewis's battery of four guns and eighty men on the plateau around the old Fitzgerald residence, at Little Falls, half a mile above the town. At 10 o'clock on Monday, the 18th, the Southern scouts were driven across the river by the enemy's cavalry, and several hours thereafter a Federal corps, of twelve thousand strong, appeared on the Stafford Heights, opposite Fredericksburg, and planted their field-batteries, consisting of more than twenty guns. Capt. Lewis's men maintained their ground and replied to the rapid firing of the enemy. The distance was short--less than half a mile. The firing of the men was accurate, yet the Confederate fire was kept up, and the Federals, uncertain as to the force opposing them, made no attempt to cross the river. Colonel Ball, with five hundred men, maintained his front, in the face of the twelve thousand Federals, encouraged by General Lee, who telegraphed him, "Hold your position if you can. Reinforcements are hurrying to you." On Tuesday, the 18th, the enemy's force was largely increased. General Burnside's whole force was pouring down to the Stafford hills. They were waiting for pontoon bridges, and did not cross the river. Meanwhile Gen. Lee's army was rushing down the roads from Culpeper and Orange counties to occupy the crest of hills around Fredericksburg. Wednesday, at daybreak, General Fitzhugh Lee's cavalry arrived. The next morning General McLaws, with his own division and that of General Ransom's, was in position, and on the 20th the Commander-in-Chief was at hand to direct the movements of the remainder of General Longstreet's command and General Jackson's corps, which rapidly followed him.