and I received instructions to prepare next day a next and shorter line in our rear, to secure us against any attempt of the enemy to interrupt the move.

On the 5th, Captain Comstock and myself prepared this line, he to the west and I to the east of the road. A continuous cover and abatis were constructed from the Rappahannock at Scott's dam around to the mouth of Hunting Run, or the Rapidan, a distance of 3 miles. This line is marked B on the map. The roads were also put in good order and a third bridge laid. A heavy rain set in about 4.30 p. m., and lasted till late at night. The movement to recross was begun by the artillery, as per order, at 7.30 p. m., and was suddenly interrupted by a rise in the river so great as to submerge the banks at the end of the bridges on the north bank, and the velocity of the current threatened to sweep them away. Captain Comstock was there to assist in this emergency. The upper bridge was speedily taken up, and used to piece out the ends of the other two, and the passage was again made practicable. Considerable delays, however, resulted from this cause. I remained behind to see to the completion and occupation of the new line. No troops, however, took up position in it except the rear guard, composed of the Fifth Corps, under General Meade, which was done about daylight on the 6th.

The pioneers from the different corps were nearly all retained by me till this time, and we soon completed the line across the road, and obstructed it with timber. I then sent them to their different corps. I cannot speak in too high terms of the energy and good-will displayed by the pioneer parties and the officers over them, with but few exceptions.

The proper dispositions were made for holding this line till all but the rear guard was past the river, and then it quietly withdrew, no enemy pursuing. The last of the army recrossed about 8 a. m. General Meade detailed General Barnes and his brigade to assist in taking up the bridges, and all were safely drawn to the top of the hill by 4 p. m., Major [Ira] Spaulding, of the Engineer Brigade, superintending.

Captain Comstock was not under my orders during these operations, but I am indebted to him for perfect co-operation in all my duties. Captain Paine, aide-de-camp, and Lieutenant Mitchell rendered most essential service in the direction and making of reconnaissances and repairing roads. Their labors carried them much under the fire of the enemy.

Very respectfully, your obedient servant,

G. K. WARREN,

Brigadier General of Vols., Chief Engineer, Army of the Potomac.

Major General D. BUTTERFIELD, Chief of Staff.

Numbers 6. Reports of Brigadier General Henry W. Benham, U. S. Army, commanding Engineer Brigade.

HEADQUARTERS ARMY OF THE POTOMAC,
Camp near Falmouth, Va., April 29, 1863.

SIR: Your attention is called to the following extract from orders issued yesterday, of which you were furnished a copy:

The bridges, two at each crossing, to be laid complete before 3.30 a. m. of the 29th, under the supervision of General Benham, who is charged with the responsibility thereof.