We left the Army of the Potomac in Maryland, at the close of the arduous Gettysburg campaign, watching the Army of the Northern Virginia, just escaped across the Potomac. Harper's Ferry had been reoccupied by Union troops as early as July 6, 1863. Meade moved his army to that place, and promptly crossing the Potomac and the Shenandoah River near its mouth, took possession of the gaps of the Blue Ridge, and marched southward along its eastern slope. Passing through Upperville and Piedmont towards Manassas Gap and Front Royal, he threatened Lee's line of retreat to his old position behind the Rapidan, and thus compelled the Confederate Army to evacuate the Shenandoah Valley somewhat precipitately. At Wapping Heights, near Manassas Gap, on the 23d of July, a somewhat lively action took place between portions of the two armies in which my troops were engaged and suffered a small loss. The enemy were driven back, and one corps of Lee's army was forced to retreat _via_ routes higher up the valley. There were lively skirmishes between the 14th of July and August 1st, at Halltown, Shepherdstown, Snicker's Gap, Berry's Ferry, Ashby's Gap, Chester Gap, Battle Mountain, Kelly's Ford, and Brandy Station, but each and all of these were without material results. By the 26th of July the Army of the Potomac arrived in the vicinity of Warrenton, Virginia, and occupied the north bank of the Rappahannock, while the Army of Northern Virginia took position behind the Rapidan, covering its fords. Both of these great armies were now allowed by their commanders to remain quiet to recuperate. Occasional collisions occurred between picket posts and scouting detachments, but none worthy of special notice. It having been determined by the War Department to enforce the draft in New York and Brooklyn, and a recurrence of the riots being again imminent, orders were issued to send veteran troops to New York harbor for such disposition and service as the exigencies might require. Western troops were mainly selected, and, with a view to sending me upon this service, I was ordered on the 14th of August to Alexandria with the 110th and 122d Ohio, the former in command of Lieutenant-Colonel Foster and the latter in that of Colonel Wm. H. Ball. On the 16th I embarked these regiments and the 3d Michigan on a transport ship at Alexandria, with instructions from Halleck to report on my arrival in New York Harbor to General E. R. S. Canby.( 2) On reaching our destination, my troops, with others from the Army of the Potomac, were distributed throughout both cities. My own headquarters were for a short time on Governor's Island, then more permanently at Carroll Park, Brooklyn.