As soon as it was ascertained that the Rebel army was in full retreat, a force of our cavalry was sent across the Potomac at Harper's Ferry, bivouacking, the night of the fourteenth of July, on Bolivar Heights. Early the next morning we advanced on the Winchester Turnpike as far as Halltown, where we deflected to the right on the road to Shepherdstown. We had not proceeded far before we encountered the enemy's cavalry under Fitzhugh Lee, with which we were soon involved in a spirited contest. At first our troopers were worsted and driven back a short distance. But, having found a good position, we rallied, and repulsed several desperate charges, inflicting heavy losses, until the Rebels were glad to give up the game, and consequently retired. Colonel Drake (First Virginia) and Colonel Gregg were among the Rebel slain, while on our side the highest officer killed was Captain Fisher, of the Sixteenth Pennsylvania. The fighting was done principally on foot. While these things were transpiring, Kilpatrick moved his division from Falling Waters to Boonsboro' by way of Williamsport and Hagerstown. Sad evidences of the recent battles and marches, in dead animals and general _debris_, were seen all along the way. Having reached our bivouac near Boonsboro', our men and horses came to their rations and rest with a wonderful relish. During the day we have been reading of the murderous riots made in Northern cities, especially in New York, where men in mobs have ostensibly leagued against the authority of the Government. The bloody accounts are stirring the rank and file of our army terribly. A feeling of intense indignation exists against traitorous demagogues, who are undoubtedly at the bottom of all this anarchy. Detachments from many of the old regiments are now being sent North to look after Northern traitors. This depletion of our ranks we cannot well afford, for every available man is needed in the field. Many of our regiments are much reduced. The Harris Light now musters but one hundred men fit for duty, scarcely one tenth the number with which we entered upon the campaign. Our horses are also much used up. Hundreds of them have been killed and wounded in battle, and not a few have "played out," so that they are utterly unserviceable. The author of these records has worn out completely two horses since he had a second horse shot under him in the cavalry fight near Upperville. _July 16._--"Boots and Saddles" sounded at four o'clock, and before daylight we were on our way toward Harper's Ferry. We revisited Rhorersville, crossed Crampton's Gap, and at last reached the Potomac at Berlin, where the division was separated, a portion of it moving to Harper's Ferry, where they bivouacked at night in the yard of the destroyed United States arsenal. Pontoons at Harper's Ferry and Berlin were used for crossing the army into Virginia. The crossing was being effected as rapidly as possible, yet for so vast an army it is always slow and tedious.