WASHINGTON, VA., July 21, 1862.

Major-General POPE:

I have just received a dispatch from Colonel Anisansel, First Virginia Cavalry, dated Culpeper, July 21. He says:

I received orders from General Hatch to strike the Richmond and Gordonsville Railroad in the neighborhood of Louisa Court-House, on Gold Mine Creek, and burn the bridge.

He started Friday, 3. p. m., with five companies of First Virginia Cavalry; arrived within 4 miles of Louisa Court-House; learned with certainly that Jackson had been there at 2 p. m. Saturday, 19th July. Jackson was received with great rejoicing, and left with 10,000 or 12,000 men by land on the State road for Gordonsville, with a large force of artillery. He left rear guard at Louisa Court-House of 3,500 men and one regiment of cavalry. Colonel Anisansel proceeded to the left of Louisa Court-House, but was informed by prisoners and contrabands that to bridges or culverts were between Gordonsville and Hannover Court-House. He failed in attempting to tear up the track for want of tools and the presence of rebel troops moving on the State road to and from. He reports that he heard the cars running, and a great stirring up was evident on his left, toward Hanover Court-House. He finally made a dash at his right, upon consultation with his officers, to destroy what he could, but encountered a heavy body of cavalry in moving one-half mile, and withdrew slowly, being ordered not to engage the enemy. He thinks they were the first Yankees in that quarter. He says he would have destroyed the bridges had he found them, and ordered officers to go back to the same neighborhood, about 50 miles from Culpeper Court-House, and destroy stores.

I have not heard of this enterprise from General Hatch, and now received the news direct from Colonel Anisansel. Have sent report of the information relating to the enemy to General McDowell and General Sigel. Your orders to General Hatch have seen forwarded to him at Culpeper.

No other news of importance.

N. P. BANKS,

Major-General.

NEAR WASHINGTON, July 21, 1862.

Major-General McDOWELL:

Wrote you to-day. Have just received dispatch from Culpeper. Colonel Anisansel, First Virginia Cavalry, reports that he was ordered to go toward Louisa Court-House and burn the bridge on Gordonsville Railroad. He left Friday, 18th, 3 p. m., and arrived within 4 miles of Louisa Court-House. Learned with a certainty that Jackson dined there Saturday, the 19th, at 2 p. m. Was received with great joy, and left for Gordonsville with 10,000 or 20,000 men and a large force of artillery by land, as he says, on the State road. Anisansel encountered a heavy body of cavalry near Louisa Court-House and withdrew to Culpeper. He reports hearing the cars running at Hanover Court-House and a great stirring up.

No other news.

N. P. BANKS,

Major-General.