Numbers 2. Report of Colonel Horace B. Sargent, First Massachusetts Cavalry, commanding detachment of First Brigade.

HEADQUARTERS CAVALRY DETACHMENT,
September 2, 1863.

CAPTAIN: I have the honor to inclose Major Cryer's report of the attack upon his patrol.

Major Chamberlain, who immediately pursued the enemy reported by him to be about 200 men, which had retired at speed into Manassas Gap, and who brought in the dead and wounded of Major Cryer's command, confirms my impression, that the clouds of dust seen yesterday were caused by the gathering of small bands of Major White's command toward the point of ambuscade, an almost impenetrable pine forest near Barbee's Cross-Roads.

To-night I might, perhaps, report that there is not an armed rebel within the circuit of country that the colonel commanding expects me to clear. To-morrow the woods may be full of them. A policy of extermination alone can achieve the end expected. Every man and horse must be sent within the lines, every house destroyed, every tree girdled and set on fire, before we can approach security against the secret combination of a sudden force within musket range of our outposts. Attila, King of the Huns, adopted the only method that can exterminate these citizen soldiers.

The people here all have sons or brothers in the cavalry. The mountains are full of men whose statements are fair, and whom nothing but infantry can capture and the Dry Tortugas control. Regiments of the line can do nothing with this furtive population, soldiers to-day, farmers to-morrow, acquainted with every wood-path, and finding a friend in every house. Regiments must bivouac among the hills, live on the country, and, if they pay at all, pay in silver for all they consume, or remain a cumbrous and unwieldy machine, or be regarded with hatred.

The rebels never patrol roads in column, and we are not safe in bands of 3 or 4; every one betrays us. The prisoner Rector is a case in point. I believe him to be a dangerous spy. He is a cripple and probably exempt, but all his sympathies and family ties are rebel, and he is a dangerous neighbor. With such men here there can be no clearing of a country of every armed rebel, with ten thousand mountain paths, and an Alsatian in every hill.

I can clear this country with fire and sword, and no mortal can do it in any other way. The attempt to discriminate nicely between the just and the unjust is fatal to our safety; every house is a vedette post, and every hill a picket and signal station.

But evidence against suspected persons, sufficient to convict them, is not easily to be obtained. I made arrests with great reluctance, and generally from signs and indications which cannot convict, but which put me on my guard.

I am very glad to receive the Third Pennsylvania, which is quite necessary over so large a line, and shall endeavor to use it advantageously in the way desired.

I have the honor to be, very respectfully, your obedient servant,

HORACE BINNEY SARGENT,

Colonel, Commanding Detachment First Brigade.

Captain A. WRIGHT,

Acting Assistant Adjutant-General.