Working from lowest to highest on the mountain, the first fortification (both chronologically and on the NPS trail of the heights) is the Naval Battery. This fortification was built in the spring-summer of 1862. It was named due to the use of IX-in Dahlgren guns shipped from the Washington Navy Yard. The battery plans (reproduced on the NPS marker on site) from 1863-64 show some seven gun positions, likely simple gun platforms, arranged in a linear emplacement conforming to the contours of the ridge fold. Photo of the plan, as displayed on the marker:
The same plan offers a key to the battery armament, listing “30 pdr Rif Dahl” and “24 smooth siege.” The former item opens a whole list of possibilities.
- First, the original IX-in guns may have been replaced by rifled Dahlgren guns. In 1863 the 100-pdr Battery higher on the mountain carried a IX-in temporally awaiting arrival of the Parrott Rifle. It is more likely one of the Naval Battery guns were used, vice requesting another such 9,000-pound weapon.
- Second, the plan’s author was in error. But the difference here in caliber is remarkable. A standard 32-pdr smoothbore bore diameter was 6.4 inches. A 30-pdr Parrott was 4.2 inches (measurement conformed with the practice of doubling projectile throw weight classifications for rifled guns). Calls into question if those preparing the plan actually saw the guns in place to begin with.
- Third, from the beginning, the battery carried rifled guns. But only one weapon fits the designation “30-pdr Dahlgren Rifle” – a “soda-water bottle” profile weapon with a 4.4 inch bore. Just over fifty were produced by Fort Pitt Foundry starting in 1864. So rule that out. The rifled Dahlgrens also used a trunnion band and breech strap, vice the standard integral trunnions mounted on rimbases used by most artillery pieces of the day (to include the smoothbore Dahlgrens).
- Fourth, when one of the original IX-in monsters was moved to the crest, it was replaced by a 30-pdr Parrott which was incorrectly identified by the plan makers. Again, calling into question the accuracy of the plan. For as anyone familiar with Robert Parrott’s work knows, the weapons are quite distinctive.
And of course option Five, that I’ve mis-understood or mis-interpreted the notations. In context, the plan may have been dafted in the summer of 1863 or later, when the Naval Battery was being down graded. The layout of the earthworks in the plan generally matches what is on the ground. But if the plan was completed after the works were dis-armed, perhaps the notation of the armament was less authoritative.
Regarding “24 smooth siege”, Gen. Barnard’s report from May 1863 identifies these as siege guns. We could quibble over the year model. The identifications are probably more academic, as the Naval Battery was converted to a stores facility when the higher batteries were constructed.
The battery was of questionable value for defense at any rate. The field of fire was limited to Harpers Ferry and some of Bolivar Heights. During the September 1862 siege of Harpers Ferry, the battery saw some use, but was abandoned when McLaws’ Division occupied the crest of the heights.
On site today, the locations of two or three of the gun platforms is apparent. Easier to make out are remains of one powder magazine. Oddly, neither the battery plan or on site traces show the use of traverses between the magazine and gun platforms. Certainly an OSHA violation!
According to Warren Ripley’s Artillery and Ammunition of the Civil Warthe IX-in gun ranged shells out to 3450 yards. Army 24-pdr siege guns could place shot out to 1900 yards (shell probably just a few hundred yards less). The same caliber siege howitzer (often called flank howitzer as I do above) fired shell out to 1300 yards. Thus Camp Hill was easily within reach of the guns, as was Bolivar Heights. Assuming the hills haven’t eroded away significantly since 1862, the battery covered very few of the Confederate’s positions. School House ridge was blocked by Bolivar Heights. Loudoun Heights would require high angle elevation of the guns to compensate for about a 400 foot difference in terrain elevation. Plunging fire upon the Murphy Farm area, and where A.P. Hill’s division flanked the Federal lines, might have been possible. But only with a high degree of coordination. I would further add, having worked indirect fire solutions in the “real world” sense, if the guns were not registered to the intended target areas, such would be very difficult. We are told that Col. Miles had not anticipated Hill’s flanking position, so I’d call into question if the battery was indeed registered to those target references.
UPDATE: See part 7 of this series.