From the little settlement of loyal Quakers at Purcellsville our line of march yesterday was by an old country road to the hamlet of Union, a hotbed of the most spiteful species of Secessionists. Union, a few days since was the scene of a brisk skirmish between Gen. Pleasonton and Stuart neither of whom accomplished much. Gen. Pleasonton says he drove Gen. Stuart, Gen. Stuart says he led Gen. Pleasonton. We lost in killed and wounded about forty, the Rebels ten or fifteen. Stuart fell back beyond Ashby Gap. Gen. Pleasonton followed throwing shell after him along the road and frightened the inhabitants into the cellars of their dwellings.

At Union a shell entered the cellar of Mr. Robey, a Methodist clergyman, and exploded but a few feet from where himself and family had sought protection. A brick partition in the cellar fortunately saved the entire group from being killed.

At the mansion of Mr Keene, one mile South of the village, I found three Rebel surgeons in attendance upon nine wounded Rebels. The surgeons and wounded soldiers were all from the famous Stuart’s division and were not at all careful to conceal their contempt for our own cavalry. The 8th Illinois, however, with whom they have frequently come in contact, they pronounced the best riders in our service, and said if they would carry less upon their horses, would make splendid cavaliers. A portion of Gen. Hunt’s brigade was also well spoken of, but they had forgotten the name of the regiment. The battle of Antietam they consider a draw game; but all and without exception that if we had fought them on Thursday their entire army would have been taken. These Rebel surgeons are educated, intelligent men, and did not seem inclined to make exaggerated statements. They stated that the capture of an entire company of Rhode Island cavalry near Aldies Gap a few days since was one of the most disgraceful affairs, for a small one, of the war. The company, according to their statement, was doing advanced picket duty, but allowed themselves to be surprised with their sabers off and their horses unsaddled. The captain of the company sprung upon the bare back of his horse and made an attempt to escape, but the horse stumbled almost instantly throwing him off and breaking his neck.

Mr Keene, the owner of the mansion where these rebel surgeons and wounded are now sojourning is about the most prominent man of the community and, of course, a leading Rebel. While he claimed protection for his property from all our Generals as their commands passed by, or over, his plantation, and obtained it, he at the same time declared that during his life he shall remain hostile to the Government of the United States. Having read much and puzzled his brains over the metaphysics of Calhoun, he enters into discussion immediately with all who approach him, from the Major General seeking his dwelling for headquarters to the guard protecting the chickens at his door. Furthermore while he boasts that he owes supreme allegiance to Virginia alone, he at the same time maintains that the Federal Government, as he calls it, is bound to pay him for his property destroyed by the army. His logic made but little impression upon either officers or soldiers, and he is this morning doubtless minus several hundred bushels of corn more than he would have if he had remained silent.

From Union, in Loudoun County, we have to-day marched to Upperville, in Fauquier County, a beautiful little village laying at the foot of the Blue Ridge and but a few miles from Ashby’s Gap. For many miles around the village the plantations are all large and the mansions generally in a good state of repair. Nearly every family has a representative in the Rebel army. All are Rebels, and not an open door or a cheerful countenance is seen. After a guard has been placed around their mansions, they sink back into a sullen taciturn mood, and do not recover from it until the last straggler has disappeared from among them.

The most prominent residents of this village tell us to-night that Gen. Lee has again outwitted Gen. McClellan; that the main portion of his army is beyond his reach, and safe behind the Rappahannock.