Battery A, 2nd U.S. Artillery

   Horse Battery A, 2d U.S. Artillery, moved from its bivouac near Keedysville on the morning of the 17th, crossed the Antietam by the Middle Bridge and preceded and supported by the 4th Pennsylvania Cavalry, went into position on the crest of this ridge about 160 yards north of this point and engaged the Confederate Artillery on Cemetery Hill and the ridge north of it. At noon it was relieved to replenish ammunition. About 3 P.M., it returned to its original position and again engaged the enemy. The right section, in charge of Lieut. A.C.M. Pennington, advanced about 650 yards, to the right and front, took position on the flank of Richrdson's Division and engaged a Confederate Battery west of the Hagerstown Pike and few yards north of where Piper's Lane intersects it. The Battery withdrew at dusk and recrossed the Antietam.