MARIETTA, August 18, 1864.

General SHERMAN:

The train, engine 142, from Allatoona, just arrived. The conductor reports as follows: As the train was nearing the road crossing, half a mile north of Acworth, they saw a small force of cavalry riding rapidly from the east toward the track. They succeeded in crossing track about thirty yards ahead of the engine. They quickly dismounted and fired upon the engine and train. The train kept on and reported to our forces at Acworth and Big Shanty. The fireman and one brakeman missing. No other force of the enemy was seen.

J. B. VAN DYNE.

LOUDON, August 18, 1864-2.20 p. m.

Captain W. P. AMMEN,

Assistant Adjutant-General.

Courier from Colonel Byrd, as Sweet Water; he says all right this far. I hear of nothing that ought to alarm us. The repairers are evidently working on line, so judge that Colonel Byrd has arrived at Athens without trouble.

N. A. REED,

Aide-de-Camp.

LOUDON, TENN., August 18, 1864-8.40 p. m.

Captain AMMEN:

Following just received from Charleston:

They seem to be principally on the north side of the Hiwassee, fording the river near Benton. The citizens report that they intend attacking this place to-night or in the morning. It is reported that they have a force of 2,000 or 5,000, with artillery.

M. B. EWING,

Lieutenant-Colonel.

From all the information we can get they are six miles above this place on the river, not very far from Benton, though most of the force is at Spring Creek, about some say the most of them have crossed the river and are marching toward Athens and Loudon.

R. K. BYRD,

Colonel, Commanding.

I have given you all that I have. The road is cut about two miles this side of Cleveland. The rebels burned and tore up the road for one mile.

R. K. BYRD,

Colonel, Commanding.

This is all we have at present. Everything is in the very best condition, in my opinion. I have visited the pickets this p. m. and found them all right; have thrown out additional advance pickets since dark; all watchful and ready. Construction train just in from Charleston. A captain of First Tennessee reports the same as telegraphs above. He says at Athens the citizens report that a brigade of cavalry passed that place on a back road three miles from town about an hour and a half before sundown, moving this way.

N. A. REED,

Aide-de-Camp.