The marker for the Fifth Army Corps is on the south side of the Boonsboro Pike, east of the Middle Bridge.

From the marker:

U.S.A.

Fifth Army Corps

Maj. Gen. Fitz John Porter, Commanding.

(September 15-16, 1862.)

 The Fifth Army Corps consisted the reserve of the Army of the Potomac. Its advance, Sykes’ Division, reached this point in the afternoon of September 15.

On the morning of September 16 it formed in the fields to the south of the Boonsboro Pike in support of the Reserve Artillery which occupied the ridge in front of this point.

Morell’s Division arrived at Keedysville about noon on September 16, and encamped in the fields west of the town.

No. 33.