LEWISBURG, VA., September 21, 1861.

To the PRESIDENT:

DEAR SIR: I took the liberty of addressing you by the last mail relative to the anxieties of our people; the proximity and strength of the enemy; the positions of our forces and their numerical strength; our generals, &c.

Since writing reports have reached Lewisburg that the enemy have crossed Gauley, and were advancing by the James River and Kanawha Turnpike eastwardly, and on yesterday they were said to be approaching the western base of Big Sewell Mountain, some 34 or 35 miles west of this. It was also said that General Wise, posted just on this side of the top of Big. Sewell, was expecting an attack. I understand that Colonel Henningsen regards General Wise's position as a strong one. I have not heard whether General Floyd has gone tot he support of General Wise. At last accounts he was at meadow Bluff, 16 miles west of this.

Our citizens were much pleased at the arrival of General Lee in our town this morning, en route for the west. He passed through, and I suppose by this time has reached meadow Bluff. He had with him only an escort of cavalry, and I have not heard of any re-enforcement to our little army being expected from Cheat Mountain. His presence in our midst has, however, given great satisfaction, as it assures us that, should the reports f want of harmony and concert have been well founded, no ill consequence can now flow from that source.

I observe that the Richmond Dispatch estimates Rosecrans' army, in the neighborhood of Gauley, at 20,000 men. I think, from all I can learn, this estimate too high, but am yet well assured that our force is entirely too small to accomplish anything of moment upon the Kanawha Valley. Availing himself of our mountain passes, I hope General Lee will be able to prevent the enemy's farther progress eastwardly, but I fear he will be compelled to abandon all offensive operations until strengthened. Could a few regiments be sent down the western side of New River to the mouth of Gauley and 3,000 or 4,000 men be added to General Wise's and General Floyd's forces form Cheat Mountain,m we might be able, I think, to cut off Rosecrans' supplies, and probably force him to a surrender. The repossession of the Kanawha Valley is a matter of very great moment to this section of country, and the occupation of Greenbrier by the enemy would, I fear, be deplorably demoralizing in its effect.

A large number of our young men are enlisted in the war, and out of our seven or eight companies two are at Manassas and one with General Loring.

I hope your excellency will do for us all in your power, for should the enemy succeed in his efforts to "hold, occupy, and possess" Greenbrier, I greatly fear that the difficulty of defending Richmond will be materially enhanced.

We started this morning for Richmond some 42 prisoners, taken by Colonel J. Lucius Davis, of Wise's brigade, in Boone County. They are a part of the miscreant band which burned Boone Court-House. Through respect to those holy laws which we are not at liberty to disobey, no matter how vile their conduct, we must extend towards our enemies the benefit of christian charity and forbearance; but truly our people have been sorely tempted, and it is no less a matter of astonishment than of rejoicing that they have so constantly manifested that noble characteristic of the brave-mercy towards the fallen.