_April 27._--Colonel Davies, after quite a lengthy absence from us, rejoined the regiment at ten o'clock A. M. He reported having a narrow escape from guerillas near Elkton, where he was fired at and pursued for some distance, while on his way from Falmouth. Details were ordered out immediately to those infested regions, with instructions to capture every thing in the shape of a bushwhacker. Captain Coon, of the Connecticut squadron, was put in command of the reconnoitring party. We had a rich and delightful ride, but did not succeed in overhauling the offenders. On the twenty-eighth the first battalion of the Harris Light, commanded by Captain Samuel McIrvin, was ordered to reconnoitre as far as Brentsville. We went via Elkton and Bristersburg, at which places we captured several guerillas, who were not looking for us. The first part of the day was very pleasant, but from eleven o'clock till night we had a continually drizzling rain, which made our march exceedingly disagreeable. We had but just halted for the night, when an order was received from a messenger, to rejoin the regiment without delay. Through the rain, mud, and darkness we hastened back to Catlett's Station, where we found every thing in motion, preparing for some grand movement. With the gray light of the morning of the twenty-ninth, after marching most of the night, we reached the banks of the Rappahannock at Kelly's Ford. In addition to the Cavalry Corps we found here the Fifth, Sixth, Seventh, and Twelfth Corps of the Army of the Potomac, making preparation to cross the river. The Engineer Corps soon laid the pontoons, and the grand columns effected a passage without material resistance or difficulty. STONEMAN'S RAID. We are credibly informed that other columns of our army are crossing the river at other points, and that a great battle is imminent. There has been occasional skirmishing, on the front, during the day. The Rebels, however, seem to have been taken wholly by surprise and are not making the demonstrations we had good reason to anticipate; but we shall be greatly disappointed if they do not soon awake, and come to their work. The going is far from pleasant, though to-day the weather is favorable. The streams are dreadfully swollen and nearly all bridgeless, compelling us to ford them. This process, through the cold, high water, is attended with more or less difficulty and suffering. Soon after crossing the river the Cavalry Corps broke away from the infantry, in the direction of Stevensburg; and it is rumored among us that a grand raid upon the enemy's communications is contemplated, while the two armies engage in deadly combat, it is thought not far from the river.