combined advance, numbering about 130 men, took possession of several dry basins along the canal and a point known as Maryland Ore Banks, which afforded an excellent shelter to my men. Thus situated, a very spirited fire was maintained for something over two hours,the fire of the enemy gradually slackening as they were dislodged by out artillery and sharpshooters, until about 6 o'clock the firing entirely ceased. (The enemy were driven from every p ont they occupied and sullenly retired beyond the range of our guns toward the interior). During this affair considerable damage was done to the mill, houses, and barns in which the rebels had taken shelter within reach of our cannon.

As far as can be ascertained through Virginia sources deemed reliable there were 18 of the rebels killed and about 25 wounded. it is impossible to ascertain exactly what the casualties of the enemy were, from the fact [that] the river divided us from them, and we have partly to rely upon the Virginians themselves for our information. Our loss was 1 killed and 3 slightly wounded. The wounds all occurred from fragments detached from the bands around the James shell, discharged by our own artillery.

The efficiency and long range of our Enfield rifles has been fully proved in this affair, and I am pleased to state they have verified our fullest expectations. Their superior accuracy and length or range over those of the enemy account in part for the small number of casualties on our side.

I am much gratified to be able to state that the troops under my command, without exception, behaved with the most admirable bravery and coolness. And I would be derelict of duty if I did not state that the highest meed of praise is due tot he company officers for the gallant manner in which they carried out every order issued and the noble emulation which animated them during the action. Several small skirmishers have occurred since, but owing tot he smallness of the numbers engaged would not justify a detailed statement.

A skirmish occurred this evening near Harper's Ferry between the rebels and a portion of troops, resulting successfully to our arms. Several of the enemy are reported killed and wounded..

A small skirmish occurred above this place, in which, it is said, one of the rebels was killed.

Respectfully submitted.

[JOHN W. GEARY,.

Colonel Twenty-eight Regiment Pennsylvania Volunteers.]

Captain ROBERT WILLIAMS, Assistant adjutant-General.

Casualties of the enemy: 18 killed and 25 wounded.

Casualties of my command:1 killed; 3 slightly wounded.

Articles captured: 2 iron cannon (12-pounder); 2 fine bay mules; 2 small brass mortars; 1 wagon; 1 prisoner, William S. eagles, second lieutenant Company K, Second Virginia Volunteers.

SEPTEMBER 16, 1861.-Skirmish opposite Seneca Creek, Maryland.

Report of Major General Nathaniel P. Banks, U. S. Army.

DARNESTOWN, September 17, 1861.

All quiet here. Nothing unusual at Poolesville up to this evening, nor above, so far as we can learn. Last night a party of the Thirty-