"They were so numerous that it looked as if they were creeping up out of the ground..." George Neese, Chew's Artillery, on Crampton's Gap

The following is a recollection from George M. Neese, a gunner in Chew's Horse Artillery. Roger P. Chew's horse battery was in position about half-way the mountainside in the area of Crampton's Gap, the primary artillery support for the Confederate defenders along the Mountain Church Road at the base of the mountain. Neese writes:

September 14- This morning the shades of night were still lingering over the landscape when we left camp, and early dawn found us on top of South Mountain, looking over the beautiful Middletown Valley that was lying before us like a diversified illuminated map, with its wooded hills, pleasant fields, hamlets, and towns reposing in the quiet calm of a peaceful Sabbath morning. But before the sun shots its first golden lance across the Catoctin range to kiss away the early dew, the booming of Yankee cannon came rolling across from the Catoctin hills, announcing in ominous thunder tones that the Yankee hosts were advancing, and that there would be but little Sunday for soldiers to-day in this part of Uncle Sam's domain. As soon as we found the whole Yankee army was on the advance, we moved about halfway down the mountain and went in battery ready to work on the first bluecoats that ventured within range of our guns The cannon we heard  so early this morning were at Jefferson, where the Yanks were shelling woods searching, I suppose,  for masked batteries, of which they were most awfully afraid. 
There are two principal gaps in South Mountain through which the main roads pass that lead west through the Middletown Valley. Turner's Gap is the most important one, as the National Road which passes through Frederick City, Middletown, Boonsboro, and Hagerstown leads through Turner's Gap, consequently the heaviest portion of the Yankee forces was hurled against the defenders of that pass to-day. We were at Crampton's Gap, which was some four or five miles south of Turner's and, judging from the small force we had there for its defense, it was not considered of much importance from a Confederate point of view. However, the Yankees did not so consider it, from the heavy force of cavalry, artillery, and infantry they brought to bear against it before the day was over. We had only three companies of infantry, Munford's brigade of cavalry, and six pieces of artillery to defend the pass against at least two, perhaps three, divisions of Yankee infantry, with accompanying artillery and a big bunch of cavalry. At about ten o'clock we saw the first of the Yankee host, about three miles away, approaching our gap cautiously and slowly. As they drew nearer the country seemed full of bluecoats. They were so numerous that it looked  as if they  were creeping up out of the ground -- and what would or could our little force of some three or four hundred available men standing half-way up the bushy, stony mountain side do with such a mighty host that was advancing on us with flying banners? As they came nearer to the mountain they threw out a heavy skirmish line of infantry on both sides of the road, and were still advancing  very slowly when their skirmish line came to within about a mile of our position , so we opened on it with our rifled guns. Our line of fire was right over the village of Burkittsville, and completely checked their skirmishers about a half a mile from Burkittsville. The Yanks now brought up a battery and opened fire on us, but they were about two miles off and all their shell fell short. I fired at them in return, but in doing I disabled my gun. The mountain where we were in battery was a little steep and my gun is a vicious little recoiler, and the recoil space of our position was too sloping, rough, and limited for a free kick, consequently with the second shot I fired--with two mile range--at the Yankees my piece snapped a couple of bolts of its mounting, entirely disabling it for the day. After my gun was damaged there was nothing for me to do but leave the field of action, but before I left I stood awhile and gazed at the magnificent splendor of the martial array that was slowly and steadily moving toward us across the plain below like a living panorama, the sheen of the glittering side-arms and thousands of bright, shiney musket barrels looking like a silver spangled sea rippling and flashing in a midday sun. 
The remainder of the battery held its position, and when the enemy advanced to a closer range opened fire and kept it up until nearly night; but late this evening the enemy forced the pass by flanking and fighting, with overwhelming numbers, and compelled our little force to retire. To observe caution with which the Yankees, with their vast superior numbers, approached the mountain, it put one very much in mind of a lion, king of the forest, making exceeding careful preparations to spring on a plucky little mouse. For we had only about three hundred men actually engaged, and they were mostly cavalry, which is of very little use in defending a mountain pass like Crampton's Gap, where there is one narrow road leading up the mountain and all the remainder of the surroundings heavily timbered  and thickly covered with regular mountain undergrowth and large, loose rocks and boulders.
Crampton's Gap is really neither gorge nor gap, only a little notch in the crest of South Mountain, and nearly all the fighting to-day in trying to defend it was done on the eastern face of the mountain. It is marvelous how a few hundred  of our men held in check nearly all day two divisions of Yankees, besides their artillery and cavalry, and I will venture the assertion that, as usual, correspondents of Northern newspapers will say that a little band of heroic Union patriots gallantly cleaned out Crampton's Gap, that was defended by an overwhelming force of Rebels strongly posted all over the mountain and standing so thick that they had to crawl over each other to get away. 
In retiring our disabled gun from Crampton's Gap we went to Boonsboro and moved southwest direction about four miles on the Shepherdstown road to our wagons, where we arrived at ten o'clock to-night, and camped. In going from Crampton's Gap to Boonsboro we passed within a half mile of Turner's Gap, where a portion of General Longstreet's forces were engaged, fighting desperately right in the gap, which the enemy was assaulting vigorously with a heavy force. The artillery fire was very heavy and the deep-toned thunder of Longstreet's guns, mingled with the crash of fierce and incessant musketry, raged and roared and rolled along the mountain slopes and made the craggy battlements of South Mountain tremble from base to crest.
Boonsboro is a pretty little town at the western base of South Mountain, on the National Road. The houses are nearly all built of brick and kept in good condition all through the town. Before we got to Boonsboro, we passed through Rorhersville, a small hamlet in a pleasant valley, three miles south of Boonsboro. We also passed through Keedysville, a small village three miles southwest of Boonsboro. 
Pleasant Valley is a beautiful little mountain vale a mile wide, extending toward Harper's Ferry along the western foothills of South Mountain. 

Neese would move with Chew's artillery through Williamsport to Martinsburg and onward toward Shepherdstown, (West) Virginia where the unit went into camp as part of the artillery reserve. On the 17th, Neese reported clearly hearing the booming of the cannon and sounds of the battle that was raging in the fields ourside of Sharpsburg. Chew's battery was ordered to Sharpsburg late in the day, arriving just as the fighting ended. The battery would remain in position until the 19th, when the Confederates retreated back across the Potomac. Neese would marched with his men over much of the Berkeley and Jefferson counties in (West) Virginia and remained in the Shenandoah Valley for the remainder of 1862.

Sources:

1. Neese, George M. Three Years in the Confederate Horse Artillery. New York and Washington: The Neale Publishing Company. 1911.

2. photo of George Neese.