An engagement took place at Aquia Creek, Va., to-day. Four vessels of the Potomac flotilla opened the attack by firing shot and shell at a new battery which had been erected by the rebels. Several of the shells fell and exploded into a camp of rebels near the battery. The rebels returned the fire with considerable vigor from rifled cannon, but caused little damage, as their range was too high. The engagement lasted three hours, during which time the flotilla was struck but by one shot, which, however, inflicted no personal injury.--N. Y. Commercial Advertiser, July 31.
Captain Wm. P. Allen, of the Eleventh Massachusetts Regiment, E. P. Doherty, of the New York Seventy-first, and Orlando Waldorf, Second Wisconsin, arrived in Washington city, having escaped from Sudley Church, Va., where they were detained as prisoners. The sentinel fell asleep, and they leaped from a window and escaped to the woods. They reached the Potomac, which they forded, fourteen miles above Washington.--N. Y. World, July 30.
The Memphis Appeal, in urging planters to keep their cotton at home, says: “Should the usual quantity be brought to Memphis — say 400,000 bales--and be stored in our warehouses this fall, the temptation for the enemy to essay its capture would be extremely great, particularly as cotton will be very scarce at the North next winter. It would be tantamount, indeed, to offering $20,000,000 for invasion of the Mississippi Valley, and for a successful invasion against Memphis.” --N. Y. World, July 31.
The House of Representatives, at Washington, refused to entertain a motion of Mr. Cox (Ohio) to appoint a Committee of Conference to report on amendments to the Constitution of the United States, with a view to the reconstruction of the Union.--(Doc. 130.)
The first regiment of the Polish Brigade, under Col. Sulakowski, left New Orleans to day for Virginia. The second regiment of the brigade is rapidly filling up, and will be in Virginia long before Lincoln, Scott & Co. make their second attempt to dine in Richmond, where Gen. Tochman now is drawing up his share of the bill of fare which the Polish Brigade intend serving up.--N. O. Crescent, July, 29.
A large meeting was held at the Merchants Exchange, in New Orleans, to make arrangements for the relief of the soldiers wounded at Manassas. Gen. W. A. Elmore presided, and Rev. Dr. Palmer spoke. Among other things he said that he did not believe this would be a protracted war. Protracted wars did not prevail among the great civilized nations of the earth, but only among barbarians. Such a war would bankrupt any nation in one year. Even England, in the war of the Crimea, found herself pressed and worried to the extreme in furnishing her army with supplies. For what duration of time could the North hope to sustain 400,000 men? As to the issue, the enemy might as well throw their millions into the rivers as to expect to subjugate us. Our cotton gave us immense power. The millions of Europe depended on it for their bread. As for the blockade, we laughed it to scorn. This war must soon terminate, or the civilized nations of Europe must become engaged in it; and he predicted our independence would be acknowledged before the first day of next year. But we would carry on this war until that end was accomplished. He alluded to a meeting at the New York Tabernacle, at which it was declared that the war should not end until Slavery was driven from our soil! But he felt it must continue until every nation on earth should recognize our independence and our institutions. He spoke of the imbecility, usurpation, and tyranny of Lincoln — unparalleled since the days of Charles I. He would have said that the North was almost unanimously against us, if he had not heard Vallandigham's voice. (Tremendous cheering.) But he felt there were many brave men at the North, who strongly sympathized with our cause. He felt the certain success of our cause, because right and truth were on our side. Not till the crush of worlds would our country be subjugated. A series of resolutions were adopted, of which the following is the first: 1. That we recognize in these victories on the side of liberty, against tyranny and oppression, the hand of the same just and righteous God who guided the armies of the country when lead by Washington in defence of its liberty; that our hearts are filled with gratitude to the most high and mighty Ruler of the Universe for that signal interposition on our behalf, manifested in the strength and courage given to our soldiers and the terror which seized upon our enemies.--N. Y. Times, August 6.
 Brigadier General Cox in a message to Governor Pierpont dated this day at Gauley, Va., says: “The Kanawha Valley is now free from the rebel troops. Most of the forces raised by Wise in this valley left him between Charleston and this place. I had sent them assurances that if they laid down their arms they might go quietly to their homes, and many lave done so, asserting that they were cheated into the rebel service. I regret to have to say that Wise in his retreat has burned a number of valuable bridges, and carried off most of the wagons and teams belonging to the people of the valley. All parties denounce him for his vandalism. I congratulate you on the success of this expedition.” --Baltimore American, Aug. 2.