The Sixth and Eighty-fourth Regiments were ordered to report at Baltimore, and the Seventy-first, assigned by our orders to my brigade, was, on its arrival at Harrisburg, also placed on detached service in another command. The reports of the commandants of the above-named regiments will show the fidelity with which they discharged the duties assigned to them . The staff organization of my brigade was as follows: Major Charles Trumbull White, assistant adjutant-general ; Major Henry D. Gardiner, brigade quartermaster; Captain Henry C. Landon, commissary ; Captain J. Hobart Herrick, ordnace officer ; Captain Reginald H. Anthon, aide. Captain Anthon, having been taken ill in consequence of severe exposure in the discharge of his duties, obtained leave of absence, and Captain Benjamin S. Church, of the Twelfth Regiment, was assigned to his post during the residue of our term of service . On the 21st of June, I was directed to proceed with the Fifth and Twelfth Regiments, numbering together about 1, 000 men, early the next day, to Marysville and Fenwick, at the junction of the Dauphin and Susquehanna Valleys, about 6 miles above Harrisburg, to guard two railroads bridges crossing the Susquehanna at that point . The Dauphin Valley runs parallel with the Cumberland Valley, being connected with it by several mountain gaps, the farthest of which is Sterrett's Gap, through which the road to Carlisle passes . The enemy being then advancing toward Harrisburg, it was supposed he might make a diversion to the left, pass down the Dauphin Valley, and cross the Susquehanna . Our position, therefore, assumed a very important character, and required very great diligence in checking a movement of that kind . On arriving at the Dauphin Valley, the only force we found there consisted of about 50 or 60 men of the Invalid Corps, stationed at block -houses near the bridges . We immediately commenced constructing such earthworks in front and flanks as were deemed necessary, and selected a position to make a determined stand, the left flank of our contemplated line being protected by an obstructions of felled woods, and the narrow pass along the Susquehanna being guarded by such force as could be spared for that purpose . Various detachments from time to time were sent with ax-men, to obstruct and guard the mountain gaps. During the service there they were exposed to almost incessant rains, having only their shelter tents to protect them from the inclemency of the whether . These detachments performed the duty assigned to them with alacrity and fidelity . During a portion of the term of service in Dauphin Valley, we were very materially aided by the Thirteenth and Twenty-eight New York National Guard, under the command of Brig. General Philip S. Crooke, and there companies of the Twenty-eight Pennsylvania Militia, under the command of Major Jessup. General Crooce and Major Jessup, with their officers and men, diligently cooperated with me in the performance of the several duties assigned to them . On the 7th of July, we proceeded by rail, with the Fifth and Twelfth Regiments, to Carlisle ; thence on the 8th and 9th, by march, by way of the turnpike, to Shippensburg. At this place, the Twentieth, Thirty-fifth, and Forty-fifth Pennsylvania Militia were attached to my brigade, then denominated the First Brigade of the Second Division of the Department of the Susquehanna, under the command of Major-General Dana, to whom I reported for duty . Under his orders the brigade was marched to a point 1 mile beyond Cambers-