of the summary report made to General Hooker of the operations of this brigade in laying and removing bridges upon the Rappahannock River during the recent eight days' struggle of this army in this vicinity.

The brigade consisted of the Battalion of United States Engineers, some 300 men; of the Fifteenth and Fiftieth New York Volunteer Engineers, about 700 men each; or, in all, some 1,700, and they were temporarily assisted by various regiments of this army at different times, varying from two to eight hours together. During this period of nine days, as will be seen by the summary, fourteen bridges (five of them relays) were placed over the Rappahannock and removed, each bridge from 100 to 140 yards long. The bridges were, first, a canvas pontoon bridge at Kelly's Ford, about 25 miles by the road above Fredericksburg or 12 in a direct line; three wooden pontoon bridges (one of them made partly of Waterman's pontoons) at the United States Ford, about 18 miles by road (or 10 in right line) above Fredericksburg; two at Banks' Ford, at about 4 miles above (these brought up from below the city); three at the city (railed after being taken up from below), and three at about 2 1/2 and two at about 5 miles below Fredericksburg. By the canvas pontoon train there passed over Stoneman's cavalry, about 9,000 strong, and this bridge was much approved, as I learn. Over the three bridges at the United States Ford there passed and repassed the bulk of General Hooker's army, with all its artillery, although the river rose some 5 feet by a violent rain, which, after the preparation for withdrawal had commenced, set in so violently as to break away one or two of the bridges.

By the two bridges at Banks' Ford, our left wing, under General Sedgwick, of about 17,000 men and fifty-five pieces of artillery, repassed in about forty-five minutes between 2 and 3 a. m. on the 5th instant, and, by the bridges at and below Fredericksburg, General Sedgwick's and a part of General Couch's corps, some 25,000 men, with their artillery, passed over to the attack.

At the laying of the first three bridges, some 2 1/2 miles, and at the next two, nearly 5 miles, below Fredericksburg, the brigade supplied the oarsmen of the boats to pass and repass for transporting the covering or protecting force, and they were consequently very greatly exposed, as also during the whole of April 29 and 30, by the accurate shell-firing of the enemy, when a shell passed through a pontoon. The engineers were also accurately shelled in laying the lower bridge at Banks' Ford on the 4th, when cables were cut, & c., and the ranges of the ravines leading to both bridges were accurately obtained and continually reached by the fire of the enemy; yet the casualties consisted of 1 sergeant killed at Banks' Ford on May 4 and 3 privates wounded at the lower ford on April 29, where my horse was shot under me, as was also the horse of Lieutenant Marsh, Fifteenth New York Engineers, under him, while we were urging forward the protecting force to cross in the boats.

An outline map* of the river and roads adjacent, which I have the pleasure of inclosing herewith, will show the position of the bridges laid, roads, & c.

I am, sir, very respectfully, your obedient servant,

H. W. BENHAM,

Lieutenant-Colonel of Engineers and Brigadier-General.

General JOSEPH G. TOTTEN,

Chief of Engineers.

---------------

* To appear in Atlas.

---------------