When it is mentioned that the Army of the Potomac required daily of the single item of forage, last winter, over 654 tons of hay and grain, some idea may be given of the immense work performed by this road. It was very successfully guarded by our troops.

On the retrograde movement of the army from Culpeper to Centreville, near the middle of October, and while it was massed at Centreville, the rebel army destroyed the road from Broad Run to the Rappahannock. Colonel McCallum came up promptly with a large construction force and repaired it in a very short time, constructing 20 miles of the road and rebuilding the bridges destroyed in twenty-six days. The army was at no time embarrassed for supplies. While the road was being our depots were at Manassas and Gainesville, and the army occupied a line embracing Warrenton; Warrenton Junction, and advance positions at Bealeton, &c.

CULPEPER CAMPAIGN.

On the 15th of September, the army was advance to Culpeper and vicinity, were it remained until the 11th of October, when the movements of the rebel army induced a rapid march of the Army of the Potomac to Centreville, as alluded to above. As this movement was a retrograde one, it became necessary to secure our trains by sending them to the rear in advance of the columns. Therefore all the trains, except the ammunition and ambulances, fell back on evening and night of the 10th beyond the Rappahannock, and parked on the two road adjoining the railroad. The army was put in motion on the 11th, the ammunition wagons and ambulances preceding their respective commands.

It was found that the enemy was marching on a line to our left nearly parallel with our own, and that the two armies were liable to come in conflict at any moment. Each appeared to be struggling to reach Centreville before the other. Under these circumstances our trains were obliged to pass on roads to our right, and to make night marches to keep well advance. On the 13th, headquarters were at Catlett's. All the trains were concentrated in one grand park at Weaverville, and ordered to make a continuous march night and day, by way of Brentsville, to Maple Valley; thence north, by Wolf Run Shoals, to Fairfax Station. They were much exposed in making this wide circuit, and were attacked on two or three occasions by guerrillas, but succeeded most splendidly in reaching Fairfax as soon as we concentrated at Centreville.

Fairfax Station was now our depot, and our wagons were in the right place. This march was conducted under the immediate supervision of Lieutenant Colonel C. W. Tolles, chief quartermaster, Sixth Corps.

The rebel army retreated, not daring to attack our position, and, tearing up and destroying the road from Broad Run to the Rappahannock, retired behind the latter stream.

The army moved forward again on the 19th of October, and on the 22nd occupied positions as follows:

First Corps, at Georgetown; Second Corps, where the Warrenton Branch Railroad crosses Turkey Run; Third Corps, at Catlett's Station; Fifth Corps, at New Baltimore; Sixth Corps, at Warrenton; Cavalry Corps on flanks; Artillery Reserve, near New Baltimore; headquarters, near Warrenton.

On the 7th of November, the army was put in motion again, and on the evening of that day captured the enemy's works on the Rap-