The marker for the Reserve Artillery of Longstreet’s Command is on the south side of the Boonsboro Pike in front of the National Cemetery. (National Cemetery tour map)

From the marker:

C.S.A.

Reserve Artilery, Longstreet’s Command 

Col. Stephen D. Lee, C.S.A., Commanding.

Organization.
Ashland Artillery Va.
Bedford Artillery Va.
Brooks Artillery S.C.
Madison Light Artillery La.
Eubank’s Battery Va.
Parker’s Battery Va.

(September 15-16, 1862.)

The Reserve Artillery crossed the Antietam about 8 A.M. of the 15th and took position on the high ground overlooking the creek to the east and south of Sharpsburg. Eubank’s Battery was posted on the bluff commanding the Burnside Bridge. At 1 P.M. the Reserve Artillery engaged the long-range guns of the enemy along the heights on the east bank of Antietam Creek. During the night of the 15th the Reserve Artillery was moved to the left, to a position near the Dunkard Church.

No. 305.