[Inclosure No. 1.]

HEADQUARTERS FIRST INFANTRY,
Camp Johnston, Va., May 31, 1861.

Brigadier-General JOHNSTON:

SIR: I have the honor to report the following information, just obtained:

The Federal troops concentrated at Chambersburg number thirteen thousand. The advance guard, of three thousand, left there at 1 p.m. for Hagerstown, where they will encamp to-night, from which force vedettes are to be thrown into Williamsport. Two companies are said to have been sent towards the river above (point not known), supposed to be at a ford. From the accompanying map you will see our position. The ford northwest of camp is susceptible of good defense. The one opposite Williamsport can be protected without difficulty by the enemy, if they have artillery.

The commanding in pencil is from a perfectly reliable source. I would wish positive instructions, and, if to make a stand, re-enforcements. My line of defense is too extended for my present force. Owing to disaffection in Captain White's cavalry, they are not as efficient as they should be, and incompetent to guard the river.

Your most obedient servant,

J. W. ALLEN,

Colonel, First Infantry.

[Inclosure No. 2.]

MARTINSBURG, VA., --- --, 1861.

According to the best information to be obtained here, Colonel Porterfield left Grafton last Monday, with his command, of about one thousand five hundred men. We went to Philippi, in Barbour County, where he probably awaits re-enforcements, expected from the valley. The U. S. troops from Wheeling, to the number of about two thousand, arrived at Mannington (forty miles west of Grafton) last Monday, and stopped to repair two small railroad bridges which had been destroyed near there. The repair of the bridges could not detain them over three of four days. Nothing definite is known here about the U. S. force advancing from Parkersburg to Grafton, but some of the railroad bridges on that line either side of Grafton on Wednesday at 4 p.m.; but some of the Union men of the neighborhood were gathering there, with such arms as they could get at home.

The above information, meager as it is, is all that we have, and is reliable as far as it goes. The bridges between this and Cumberland should by all means be burned (especially the bridge over the Potomac proper). Small bridges are but a small hinderance, in point of time, to an army, and recollect the railroad is to be the means of precipitating the immense body of men from Ohio and west of Ohio, who are to occupy our Virginia. Only important bridges will present obstacles, as to time, of any material value. West of Cumberland there are also important bridges, but I fear they are in the hands of Union men, and a little force would be required.

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