This morning a general order was issued at Fairfax Court House, Va., by General McDowell, deprecating the disorderly conduct of the troops under his command in destroying the property of the inhabitants of the town, and appointing a police force from each regiment to secure the preservation of such property. It was read to every regiment in the army of the Potomac.--(Doc. 100.)
A large and enthusiastic Union meeting composed of the citizens of Broome and Chenango counties, New York, was held to-day. Addresses were made by Daniel S. Dickinson and George Baillet, and resolutions approving the acts of the Federal Government in the present crisis, were unanimously adopted.--(Doc. 101.)
The Tammany Regiment or Jackson Guard, N. Y. S. V., under the command of Colonel Wm. D. Kennedy, left its encampment at Great Neck, Long Island, for the scene of the war.--N. Y. World, July 19.
In the House of Representatives, Washington, the Committee to whom was referred the resolution to inquire whether or not the Hon. Henry May, of Maryland, was in criminal intercourse with those in armed rebellion against the Government, submitted a report that there was no evidence of Mr. May's guilt in that particular, the resolution having been based on mere newspaper statements. The report also exculpated the President and General Scott from all suspicion of a correspondence with the rebels through Mr. May's agency. Upon the adoption of this report, Mr. May addressed the House upon the subject of the inquiry, warmly denouncing it as an unparalleled outrage upon his constituents, whose rights as freemen, he said, had been previously stricken down and trampled in the dust by the Administration, through its military power. His remarks were interrupted by Mr. Stevens, of Pennsylvania, who interposed a point of order, which, being sustained by the House, Mr. May declined to avail himself of the permission to proceed in order, announcing his purpose to vindicate himself on a future occasion. He presented the memorial of the Police Commissioners of Baltimore. Ex-Governor Thomas, of Maryland, replied to Mr. May in a vigorous speech, in which he maintained that the recent election demonstrated conclusively the fact that a vast majority of the people of Maryland entirely approved the military measures of the Administration, and of the present attitude of the State. In the United States Senate the bill for the better organization of the military establishment being under consideration, Mr. Powell  moved an amendment declaring that no part of the Army or Navy should be used for the subjugation of any sovereign State, or in any way to interfere with African slavery. A sharp debate followed on the purposes of the war. Mr. Sherman, Republican, said the war was not one of subjugation, but merely intended to maintain the integrity of the Union, and moved as a substitute for Mr. Powell's amendment a resolution declaring that “the military be employed to preserve the Union and protect the public property.”
The Philadelphia Press of to-day contains an interesting account of affairs in Richmond, Va. It will be seen that the steel-clad steamer Yorktown is about to attempt to force her way through our fleet, and that infernal machines are being prepared to injure our vessels and forts. A very decided reaction in public sentiment among the working classes has recently occurred, and, like many of the troops, they are heartily sick of the Secession movement, and anxious for the re-establishment of the National authority over the whole country. The slaves are well apprised of the movements of our army, and many of them earnestly desire its success. Several regiments have recently been sent from West Tennessee into the eastern part of that State to overawe the Union men there. The effects of the blockade are seriously felt, but some important articles are still obtained from the North.--(Doc. 102.)
This afternoon Major Van Horn's command of United States Reserve Home Guards of Kansas City, Mo., numbering about 170 men, was attacked by 500 rebels under Capt. Duncan, thirteen miles north of Harrisonville. The fight lasted four hours, during which time a continued firing was kept up on both sides. At twenty minutes past six o'clock the rebels withdrew, leaving the United States troops victorious. The loss of the rebels was fourteen killed, including two officers, and several wounded; while that of the United States forces was only one killed. At 12 o'clock the United States troops continued their march, crossing Grand River, but they were compelled to leave three of their baggage wagons on the bank of the river in consequence of high water. Major Van Horn left Kansas City on the 17th for the purpose of reinforcing Maj. Dean, now holding West Point, Missouri, with a small force, he having routed 1,000 rebels at that place. Major Van Horn's command was attacked while at dinner. They planted their flag-staff at 2 o'clock, never giving way an inch nor removing the flag till after the rebels withdrew. The rebels endeavored to flank them on the left with a company of cavalry, but were completely routed by a detailed force under Captain Butler.--N. Y. World, July 23.
The Federal army left Fairfax Court House, Va., this morning and took up its line of march in the direction of Centreville. General McDowell, in a despatch to Headquarters at Washington, gives the position of the several divisions of his army to day.--(Doc. 103.)
An engagement took place at Blackburn's Ford, four miles south of Centreville, Va., this afternoon. General Tyler's division encamped last night a few miles east of Centreville, and this morning proceeded toward that point. Centreville was passed in safety, and the troops turned from Little River turnpike road to the Manassas road. On the road information was received that a masked battery was on the left of the road ahead, and Colonel Richardson, in command of the Fourth Brigade, was ordered to reconnoitre, while the remainder of the division remained in the vicinity of Centreville. Col. Richardson proceeded with three companies of the Massachusetts First Regiment, being the Chelsea company, the Fusileers, and the National Guards. They passed across an open ravine and again entered the road, which was densely surrounded by woods, when they were received by a raking fire from the left, killing a number of the advance. They gallantly sustained their position and covered the retreat of a brass cannon of Sherman's battery, the horses having been completely disabled by the fire, until relieved by the Michigan Second, and the New York Twelfth Regiments, when they fell back. The Federal forces then took a position on the top of a bill. Two rifle cannons were planted in front, supported by Captain Brackett's Company B, Second Cavalry, with a line of infantry composed of the Second Regiment of Michigan, and the Twelfth Regiment of New York in the rear. A steady fire was kept up on both sides in this position. The rebels had two batteries of eight pieces in a position commanding the road. They used their guns well, except that they fired  sometimes too high,--but they were gallantly forced by the national troops. “They did not reply to our regular fire for half an hour,” says a correspondent, “during which time they were receiving large reinforcements. In the mean time Col. Richardson's brigade reconnoitered the woods. While we were again thus advancing we were met with a raking fire. Our guns were again put in position, and we poured grape and canister among the enemy till the supply was exhausted.” At half-past 4 o'clock, General Tyler ordered his troops to retire, it being necessary to relieve Captain Brackett's cavalry, which had done the most effective service. The day was exceedingly hot, and the horses thirsted for water, which could only be obtained at Centreville.--(Doc. 104.)