also ordered General Field's (First) brigade, now on my left and rear 7 miles, to move to my front and right in the direction of Fredericksburg and Port Royal. All the cavalry I have (between 400 and 500) is attached to his brigade, with which he will watch the movements of the enemy up and down the river. It is too small for the service, but I am satisfied the officers will make the best use of it possible. I want cavalry in front of Milford to scour the valley all the way down to Tappahannock.

I have the honor to inclose a memorandum given me by a respectable citizen of Fredericksburg (Mr. Richards) fleeing from that place, who will be in Richmond to-morrow, and respectfully suggest that as Cueto has made the impression in Fredericksburg that he is a spy, it may be will to send for Roberts to confront him.

I have the honor to be, general, your obedient servant,

J. R. ANDERSON,

Brigadier-General, Commanding.

[Inclosure.]

FREDERICKSBURG, April 28, 1862-12 o'clock.

DEAR SIR: Within half an hour I sent a letter addressed as this, believing it important that you should be immediately advised:

1st. The enemy have refused any communication with their side to-day, and for the first time.

2nd. It is apparent that the enemy's force opposite to us is much diminished.

3rd. Respectable citizens heard great knocking and hammering during the night, as if breaking up.

4th. A regiment of cavalry is now passing down the river opposite us.

5th. General McDowell arrived at Chatham from Washington on yesterday.

6th. It is said a large number of troops landed at Boyd's Hole, King George, and at Potomac Creek, 9 miles from here, on yesterday.

7th. It is certain that the enemy have had spies and one mounted scout through this country, as a respectable citizen saw him swim his horse across by the side of the ferry-boat.

8th. Another respectable citizen heard a negro, who had been connected with the railroad line, tell a group of the enemy in their camp yesterday that we had from 5,000 to 10,000 men at Guiney's, and that more were coming.

9th. It is safe to conclude that the enemy are fully informed of the numbers and position of our troops.

10th. Intelligent citizens say that 10 to 12 miles below this are places of crossing the river which will put the enemy within 8 miles of Guiney's and 15 of Milford.

11th. And that it is the strategy of the enemy which, with a few hours of forced march, threatens disaster to our troops.

12th. That some movement is now in progress by them you may rest assured, and that they expect to take our troops by surprise by such flank movement seems most probable.

13th. An intelligent citizen some four or five days ago heard a soldier say that in ten days the term of his regiment (Fourteenth New York) would be up and then they return home. Perhaps this movement is attempted that by success they may retain them.

With much respect,

T. B. BARTOW.