left us very deficient in cavalry here. As soon as Stuart's approach was known, however, one of these regiments was ordered back, but has not yet arrived.

GEO. B. McCLELLAN,

Major-General.

Major-General HALLECK,

General-in-Chief.

Numbers 3. Report of Major Albert J. Myer, Chief Signal Officer, U. S. Army.

HEADQUARTERS ARMY OF THE POTOMAC,
Camp near Knoxville, Md., October 21, 1862.

SIR: I have the honor to submit the following report of operations of the Signal Corps of the Army of the Potomac, as reading to the recent passage of the lines of this army by a rebel cavalry force, under Major gen. J. E. B. Stuart:

Early on the morning of October 10, 1862, a force of cavalry and artillery, estimated, by the signal officers who afterward saw them, as consisting of four regiments of cavalry and four guns, crossed from Virginia into Maryland at the McCoy Ford [Ferry] of the Potomac. The officers at the signal station on Fairview Heights were, about 8 o'clock a. m., attacked by a party of about 20 of this cavalry, detached for that purpose, and were so nearly surprised at their station as to lose 2 privates, taken prisoners, and nearly all of their signal equipments. I refer for details to the inclosed report (A) of Lieutenant W. W. Rowley, acting signal officer, in charge of Fairview Station. It does not appear that these officers can be held blamable for a neglect of duty. According to the statement submitted, the valley of the river was, on that morning, obscured by fog. The river itself, the roads in Maryland leading from the ford, and the road by which the enemy the station were not visible from any point upon the mountain. The officers were not notified by any pickets or others as to the approach of the enemy. I am not informed whether the enemy ought to have been seen in Virginia approaching the river, and prior to crossing.

Upon being driven from the station, Lieuts. W. W. Rowley and W. B. Roe, acting signal officers, rode to Clear Spring, a distance for 3 miles from the station and there reported the facts to Captain Russell, of the First Maryland Cavalry, who immediately sent the dispatch to General Kenly, commanding at Williamsport. Lieutenant Rowley also dispatched a courier, with a statement of facts, to the signal station near Hagerstown, in charge of Lieutenant J. H. Spencer. This courier arrived and reported to Lieutenant Spencer at about 11 a. m. Lieutenant Spencer at once reported the fact to General W. T. H. Brooks, commanding at Hagerstown, Lieutenants Rowley and Roe themselves arrived at Hagerstown at about 2 p. m., when they made a statement of facts, giving the probable force for the enemy and the number of his guns to Generals Franklin and Brooks, then at that place. A hasty report,in writing (C), made by them at that place, and addressed to me a these headquarters, is timed 2 p. m. of that day.

At about 12 p. m. of October 10, I had the unofficial information of the crossing at these headquarters. the orders, of which the inclosure