Fortification Friday: Embrasures to protect the gunners

Over the last few weeks, we’ve looked at the placement of artillery in the field fortification, in what is called batteries.  The first option explored was a barbette mounting, where the cannon fired over the parapet.  Such an arrangement offered a wide field of fire.  But it also exposed the cannon crew to enemy fire.  Another alternative was to provide openings in the parapet through which the cannon could fire.  Thus allowing the gunners to remain behind the parapet as they worked the cannon. So let’s circle back to Mahan, who defined these openings along with introducing terms to describe the components:

The embrasure is an opening made in the parapet for a gun to fire through.  The bottom of the embrasure, termed the sole, is two feet nine inches, or four feet above the ground, on which the wheels of the carriage rest, according to the size of the gun; it slopes outward to allow the gun to be fired under an inclination, the base of this slope should never be less than six times the altitude….

I hate to interrupt the professor mid-sentence, but it is a run-on.  And we need to consider these components of the embrasure in turn.  Allow me to use the diagram from Mahan’s post-war instruction (which is somewhat cleaner for purposes of highlighting these parts of the embrasure):

MahanFig33

What we see here is two sub-diagrams depicting a section of the parapet on which an embrasure is placed.  On the right is the plan, or the fortification as seen from directly above, laid out across the horizontal plane.  On the left is the elevation, or vertical.  I’ll put a solid blue line between the two sub-diagrams for clarity, and indicate where the sole is located:

MahanFig33_Sole

On the right, the sole is C-D-I-K.  On the left, the sole is line a-b.  In simple terms, we might consider the sole to be the floor of the embrasure.  So the cannon will be firing over the sole.  Thus we have two properties to consider.

First is the height of the sole respective to what would be the tread of the banquette, or interior behind the parapet.  Mahan tells us “two feet, nine inches or four feet” depending on the size of the cannon. Recall that is the same measure specified when considering the height of the mound behind the parapet for barbette positions.  Yes, properties of the cannon and carriage remain the same, but we are applying those measures in different ways.  For a barbette, that specified the measure from the interior crest down to the mound of earth (and thus determined how high the mound of earth needed to be).  For a parapet, that specified the measure from the interior edge of the sole down to the tread. Another way to look at it, when building an embrasure the measure of two feet, nine inches (or four feet for the bigger gun) determines how deep the embrasure is cut into the parapet.  Regardless of barbette or embrasure, the cannon’s muzzle needed to have clearance to fire some 33 inches above the flat ground on which the carriage (wheels) sat. Got that?

The second property to consider is the horizontal lay of the sole as it extends through the parapet.  To allow declination, the sole had to slope down from the interior edge. So we have to think about how that opening is defined and regulated, as Mahan continued:

… the interior opening, termed the mouth, is from eighteen inches to two feet wide, according to the caliber of the gun, and is of a rectangular form….

Turning back to our diagram, here is the mouth:

MahanFig33_Mouth

On the right, that’s under I-K-O-P; to the left a triangle from a-d-unlabeled point.  This mouth was a foot-and-a-half to two feet wide.  The “gun books” tell us 6-pdr field gun muzzle swells are 8.25 inches in diameter.  The muzzle band on the 32-pdr field howitzer is 11 inches in diameter. Later models of the 24-pdr siege gun had a muzzle swell out to 15.5 inches. Going to the extreme end, 32-pdr and 42-pdr seacoast guns have muzzle swells to 15.5 inches and 17 inches, respectively.  So you can see where 24 inches (two feet) would give adequate clearance for the largest guns that could possibly be used in a field fortification… at the time Mahan was writing that is, as the big Parrotts and Rodmans were not yet in service.

From the mouth, the sole will decline outward as we noted above.  Furthermore, it should also expand wider to allow some traverse for the gun.  And the professor had a word for that widening of the sole:

… the embrasure widens toward the exterior, which widening is term the splay….

The splay is not necessarily a “part” but more so a specification applied to the embrasure.  But here’s where that specification would play out on the diagram:

MahanFig33_Splay

If I had fancy 3-D modeling, you’d have a cool animation spinning about to show how this splay opens outward.  Sorry, I don’t so you’ll have to go visit a fort for that.  But you get the idea of where the splay is employed.  But as with all parts of a fortification, the splay had natural limits, lest it be too great or too small… or grossly impact other components:

… the manner in which the splay is regulated, is by producing the sole to the exterior slope of the parapet, and making this exterior line measured on the sole, equal to half the distance between the inner and outer lines of the sole. This construction makes the sole a trapezoidal figure, the side of the trapezoid, on the interior being eighteen inches, or two feet; the opposite side being equal to or half the perpendicular distance between the two sides.

We fixed the mouth at between 18 and 24 inches.  To set the exterior opening’s size, take a measure from the mouth to the front (line C-D in the diagram, but not necessarily correlating to the front of the parapet mind you).  Half of that measure will give you the necessary width of the exterior opening.

So it is important to have a line defined that is perpendicular to the mouth, running directly out the embrasure.  What do we call that?

The line which bisects the sole is termed the directrix of the embrasure….

And we see that on the diagram:

MahanFig33_Dtrx

Since this is a 3-dimensional feature, the embrasure must have sides for the trapezoidal sole.  What are those called?

… the sides of the embrasure, termed the cheeks, are laid out by setting off two points on the exterior crest of the parapet, one on the right, the other on the left of the sole, so that the horizontal distance of these points from the sole shall be equal to one-third their height above it.  Lines are then drawn on the exterior slope, from these points to the exterior points of the sole; lines are in like manner drawn from the same points, on the superior slope to the upper points of the mouth, on the interior crest.  These four lines form the boundaries of the two cheeks on the superior and exterior slopes.

So let me highlight the cheeks on the diagram:

MahanFig33_cheek

Note how these cheeks are also sloped… maybe we include that as part of the splay… to allow better clearance.  What we are defining here with the embrasure is not only the opening that the cannon’s muzzle will use, but also the opening that the projectile will exit the fortification.  Thus it is rather important to provide ample clearance!

Having identified the components and some of the properties of embrasures, let’s take a step back and consider how these were used.  Yes, the gunners now had a parapet between them and the attackers. But as laid out between the cheeks and sole, the splay also limited the field of fire.  Thus embrasure placement was very important.  One might set the directrix to be perpendicular to the line of the parapet.  Or perhaps the situation required an off-set angle, or oblique, to best cover a particular corner of the works.  Thus embrasure construction was not simply digging out some “windows” for the fort.  As these embrasures would define what sectors the big guns could dominate, the engineer and artillerist had to work together in order to get the most out of the emplacement.  We’ll look at that in the next installment.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 54-5.)

Summary Statement, 1st Quarter, 1863 – Michigan Artillery

The Wolverine State sent a full regiment of light artillery to war along with a couple of independent batteries.  But for the first quarter of 1863, only ten of those were on the rolls.  As mentioned in the review of the previous quarterly summary for Michigan, the Ordnance Department clerks used designations for independent batteries (i.e. 1st Battery, 2nd Battery), while other official records consider these as regimented batteries (i.e. Battery A, Battery B).  I’ll use regimental designations here, but call to reader’s attention the this should be a natural match – as 1st Battery appears to be Battery A; 2nd Battery as Battery B; and so on:

0116_1_Snip_MI

In addition to the ten light batteries, there are two separate sections to consider (and hopefully identify):

  • Battery A (1st Battery): No return.  This should be Lieutenant George Van Pelt’s battery, assigned to First Division, Fourteenth Corps.  A February 1863 roll-up of all artillery in the Department of the Cumberland indicates the battery had five 10-pdr Parrotts.
  • Battery B (2nd Battery): Reporting from Bethel, Tennessee with two 12-pdr howitzers and three 3-inch rifles. Long story short on this battery’s history – having been overwhelmed at Shiloh the previous spring, it had just reconstituted and returned to duty.  The battery, under Lieutenant Albert F. R. Arndt, was posted to West Tennessee, under the District of Corinth, in the “catch all” Sixteenth Corps.
  • Battery C (3rd Battery): At Corinth, Mississippi.  One 12-pdr field howitzer and three 10-pdr Parrotts.  Under Captain George Robinson, this battery was also part of the District of Corinth, Sixteenth Corps during the winter of 1863.
  • Battery D (4th Battery): Reporting somewhere in Tennessee, which I cannot make out. Two 12-pdr field howitzers, two 10-pdr Parrotts, and two James 3.80-inch rifles.  Assigned to the Third Division, Fourteenth Corps, under Captain Josiah Church, which was of course at Murfreesboro at the time in question.
  • Battery E (5th Battery): At Nashville, Tennessee with three 6-pdr field guns and two 10-pdr Parrotts. Captain John J. Ely’s battery was part of the Artillery of the Reserve Corps, Army of the Cumberland, and then serving in the garrison of Nashville.
  • Battery F (6th Battery): Munfordsville [sic], Kentucky. Two 6-pdr field guns and two 10-pdr Parrotts.  Records show that one section was at Munfordville under Lieutenant Luther F. Hale with two 6-pdrs and two 10-pdr Parrotts.  Another section was at Bowling Green under Lieutenant Byron Paddock also with two 6-pdrs and two 10-pdr Parrotts.  So did only one section report?  Or should we look to one of the separate sections entered separably?
  • Battery G (7th Battery):  At Vicksburg, Mississippi… which it indeed visited later in July!  But this battery spent the winter of 1863 between Young’s Point and Milliken’s Bend, Louisiana, as part of the Ninth Division, Thirteenth Corps.  The summary indicates six 3-inch Ordnance Rifles on hand.  Captain Charles H. Lanphere commanded (Lieutenant Robert M. Wilder held the command temporarily during the winter).
  • Battery H (8th Battery): At Milliken’s Bend, Louisiana with with two 12-pdr field howitzers, two 6-pdr (3.67-inch) rifles, and two James (3.80-inch) rifles.  Captain Samuel De Golyer’s battery was assigned to Third Division, Seventeenth Corps.
  • Battery I (9th Battery): Reporting at Fairfax Courthouse, Virginia with six 3-inch rifles.  Captain Jabez J. Daniels commanded this battery assigned to the Cavalry Division of the Department of Washington.
  • Battery K (10th Battery): Arriving at Camp Barry, Washington, D.C. at the end of the winter.  The battery reported two 12-pdr field howitzers and four 3-inch steel rifles. Captain John Schuetz commanded this battery through the war.

With the organized batteries out of the way, let us turn to the two section entries:

  • Finch’s Section: Hickman’s Bridge, Kentucky. Two 12-pdr field howitzers.  Lieutenant Amasa. J. Finch of the 18th Michigan Infantry had charge of a section in the District of Central Kentucky. This was a temporary assignment, apparently disbanded before the end of the March.
  • Section at Munfordville – Clearly indicated as at Munfordville and with three 10-pdr Parrotts.  The “name” column may be “Boyd’s” or other common name.  But without any other leads, all I will commit to is this line referenced a three-gun section at Munfordville.

With that, question tabled, we can turn to the smoothbore ammunition reported:

0118_1_Snip_MI

With a lot of 6-pdr field guns and 12-pdr field howitzers to feed:

  • Battery B: 152 shell, 152 case, and 94 canister for 12-pdr field howitzers.
  • Battery C: 30 shell, 80 case, and 35 canister for 12-pdr field howitzers.
  • Battery D: 98 shell, 108 case, and 40 canister for 12-pdr field howitzers.
  • Battery E: 206 shot, 133 case, and 137 canister for 6-pdr field guns.
  • Battery F: 258 shot, 209 case, and 115 canister for 6-pdr field guns.
  • Battery H: 240 shell and 63 canister for 12-pdr field howitzers.
  • Battery K: 156 shell for 12-pdr mountain howitzers; 204 shell for 12-pdr field howitzers; and 48 shell for 12-pdr Napoleons.
  • Finch’s Section: 192 shell, 192 case, and 128 canister for 12-pdr field howitzers.

Battery K’s quantities raises eyebrows. Then again, the battery was in the “school house.”

Moving to the Hotchkiss rifled projectiles:

0118_2_Snip_MI

Note the calibers and quantities cited here:

  • Battery B: 48 canister, 48 percussion shell, 72 fuse shell, 240 bullet shell for 3-inch rifles.
  • Battery G: 202 canister, 156 percussion shell, 252 fuse shell, 600 bullet shell for 3-inch rifles.
  • Battery H:  281 shot and 130 percussion shell for 12-pdr Wiard (3.67-inch) rifles.
  • Battery I: 96 canister, 200 percussion shell, 400 fuse shell, 720 bullet shell for 3-inch rifles.
  • Battery K:  96 canister, 165 percussion shell, and 165 fuse shell for 3-inch rifles.

First off, we see an abundance of case shot (bullet shell) for a couple of batteries. As for Battery H, those are not Wiard projectiles but rather Hotchkiss type that were made for a specific caliber.  That caliber happened to be associated closely to Wiard’s guns… at least by the clerks counting things. Clearly those were meant for use in the 3.67-inch rifled 6-pdrs.  This is also an indicator we’ll see Tatham’s columns used later.

On the next page, we can focus on just the James, Parrott, and Schenkl projectiles:

0119_1A_Snip_MI

The full page is posted, if you need reference.  But let us look specifically at the quantities reported.  First the James patent projectiles:

  • Battery D: 12 canister for James 3.80-inch rifles.
  • Battery H: 97 shell for James 3.80-inch rifles.

Now the Parrott patent projectiles:

  • Battery C: 40 shell, 382 case, and 126 canister for 10-pdr Parrott.
  • Battery D: 150 shell, 150 case, and 45 canister for 10-pdr Parrott.
  • Battery E: 196 shell, 129 case, and 47 canister for 10-pdr Parrott.
  • Battery F: 422 shell, 381 case, and 92 canister for 10-pdr Parrott.
  • Munfordville Section:  417 shell and 150 canister for 10-pdr Parrott.

Lastly, the first set of Schenkl projectile columns:

  • Battery C: 57 shot for 10-pdr Parrott.
  • Battery E:  33 shot for 10-pdr Parrott.

And there is one more Schenkl projectile entry line listed on the next page:

0119_2_Snip_MI

  • Battery D: 333 shell for 3.80-inch James.

And on the far right, the Tatham canister columns:

  • Battery H: 186 canister for 3.67-inch rifles; 41 canister for 3.80-inch rifles.

Yes, that 0.13-th of an inch mattered.

Finally, we can turn to the small arms on hand for the winter reporting period:

0119_3_Snip_MI

By battery:

  • Battery B: Thirty Army revolvers and thirty-one cavalry sabers.
  • Battery C: Eighteen cavalry sabers.
  • Battery D: Twenty cavalry sabers.
  • Battery E: Ten horse artillery sabers.
  • Battery F: Twenty-five Army revolvers and twelve cavalry sabers.
  • Battery G: Fifteen Army revolvers, fifty-eight cavalry sabers, and six horse artillery sabers.
  • Battery H: Fifty cavalry sabers.
  • Battery I: 141 Army revolvers and thirty-three horse artillery sabers.
  • Battery K: Fifteen Army revolvers and 128 horse artillery sabers.
  • Finch’s Section: One Army revolver and three cavalry sabers.
  • Munfordville Section: Two Army revolvers.

The biggest question mark for the Michigan summary in this quarter is that Munfordville section. Oh… bad penmanship of some clerk 153 years ago!

153 years ago today: A “Coal Black” Swamp Angel delivered 36 shots of retribution

In the early morning hours of August 22, 1863, a Federal gunner pulled a lanyard attached to a friction primer.  That action launched a 8-inch Parrott shell from this muzzle:

Trenton 14 Aug 10 373

The gun was aimed at Charleston, South Carolina, using rough estimates and the city’s church spires as reference points.  The projectile flew for about thirty seconds to a range close to 7,500 yards (over four miles).  Thirty-five shells followed until, on the following night, the gun failed and burst.

But the Swamp Angel had served notice.  Such was the first of many rounds to follow as Federal batteries targeted Charleston during the remainder of the war.  As I related back on the 150th of the event, for proper context we must look at this episode from several angles.

We often see the Swamp Angel connected to notions of lost chivalry and abandonment of conventions of war.  Wistfully, the angle is to say the Swamp Angel was firing on defenseless civilians, as the Federals were impotent to move the Confederates on the battlefield.  And there is some foundation to that charge.  Major-General Quincy Gillmore tied the bombardment to a demand for Confederate withdrawal from Morris Island.  However, before we start drawing war crime charges for Gillmore consider since the advent of gunpowder western armies had threatened and bombarded cities as leverage to demand the withdrawal (or surrender) of a defender.  In fact, such practice dates gunpowder and cannon, going back to days of trebuchets, catapults, and… well bow and arrow!  And always there was a fine hair to split – were the defenseless citizens legitimate targets, as they aided the defenders in some way… or were they afforded protection?

But there is more to consider here than just some barbaric act.  Charleston was a major base of supply for the Confederate war effort.  The stubborn resistance at Battery Wagner was only possible with nightly resupply from Charleston.  Factories produced all manner of supplies feeding the Confederate war effort.  Cannon produced and modified in Charleston bolstered the defenses ringing the city.  Ironclads under construction, to add to the already large squadron, sat on the ways.  There is no disputing that Charleston was a large cog in the Confederate war machine.  And that status made it a legitimate target.

Yet, as we read accounts of those who manned the guns which fired on Charleston, there seems to be a deeper justification of the bombardment. Indeed, an attitude which is seen even from northerners well beyond and detached from the battlefield.  As Melville put to verse, to many this was about retribution.  Charleston had sinned and had to be punished. The very name given the gun – Swamp Angel – calls that notion.  Consider the opening verse:

There is a coal-black Angel
With a thick Afric lip,
And he dwells (like the hunted and harried)
In a swamp where the green frogs dip.
But his face is against a City
Which is over a bay of the sea,
And he breathes with a breath that is blastment,
And dooms by a far decree.

Regardless of the perspective you chose to emphasize, we are lucky to have physical reminders of the Swamp Angel and the bombardments that followed.  The site of the battery is marked and can be found today by intrepid visitors, provided they have a boat and can navigate the flats.  Several shells have been excavated from Charleston over the years and are on display in museums.  But most prominently, the scrap iron remains of the Swamp Angel were set aside for a memorial:

Trenton 14 Aug 10 381

It is fitting, I think, the gun remains “coal black” as the day it fired on Charleston.  Likewise fitting, for many reasons, that it retains its jagged crack.

Fortification Friday: Let’s put more guns in barbette batteries on the bastion

Last Friday we walked through the process of placing a gun, in a barbette battery, to cover the capital of a bastion (in other words… at the point of the salient).  Such is a significant improvement of a defense, as it allows the defender to put firepower on the “sector without fire” and address one of the inherent flaws of the bastion.  If setup by the numbers, the emplacement looked as such (ignore “Figure E” to the left for the moment):

PlateIVFig32W

Such is good news for the defender.  But the artillerist is quick to point out, that’s a rather exposed position.  To cover that gun on the capital, the defender would want to place additional guns in the bastion, on the faces.  This would not only afford counter-battery fire on any attacker cannon aimed at the point, such would also bolster the firepower of the faces of the salient.

With that expressed need in mind, consider the next paragraph from Mahan:

If three more more guns are placed in the salient, a pan-coupé is formed as in the last case, and twenty-four feet are in like manner set off on the capital but instead of proceeding as in the last case, a perpendicular is drawn from this point to each face, and the pentagonal space, thus enclosed, will be taken for the gun in the salient; from the perpendiculars last set off, as many times sixteen-and-a-half feet will be set off on the interior crest of each face, as there are guns required:  this will give the length of the barbette along each face; the depth will be made twenty-four feet, and the two will be united in the salient.  One of more ramps may be made as most convenient.

So to add those additional guns, we start with the barbette on the capital as established before:

PlateIVFig33_A

Note here the ramp is removed from the first barbette, so we have a pentagon to work with, instead of a hexagon.

Next step is to allocate space to the sides of that pentagon on a parallel of the parapet:

PlateIVFig33_B

This is 24 feet back of the parapet, to confirm to the depth of a standard barbette. Note this is the “mound” or built up area prescribed for a barbette, and should bring elevation up to at least “two feet nine inches below the interior crest for guns of small caliber, and four feet for heavy guns.”

Next the engineer would allocate a frontage of 16 ½ feet (what Mahan wrote) or 18 feet (what Mahan put on his diagram) for each gun:

PlateIVFig33_C

Confusion over the correct dimensions?  Not really.  Recall 16 ½ feet was for field guns and 18 feet was for siege guns. Both requirements appear to be offered interchangeably in the instruction.  In those frontages, we see the platforms (C) for the guns.

With those defined, in the case of our diagram, there are two barbette positions on each face:

PlateIVFig33_D

But… how do we get the guns up there?  Oh… the ramps:

PlateIVFig33_E

These would be ten feet wide and with a 1:6 slope.  Granted, if it were me those would be dressed a lot cleaner to avoid twists and turns.  Anyone who’s moved a couch into a small apartment door might relate.

Great!  We have a battery with five guns in barbette on the salient angle of the bastion. But everything has pros and cons.  So let us assess:

The advantages of the barbette consist in the commanding position given the guns, and in a very wide field of fire; on these accounts the salients are best positions for them.  Their defects are, that they expose the guns and men to the enemy’s artillery and sharpshooters.

Light guns, particularly howitzers, are the best for arming barbettes; because the hollow projectile of the latter is very formidable, both to the enemy’s columns and to his cavalry; and when his batteries are opened against the salients, the light pieces can be readily withdrawn.

See, it would be nice to have the ramps setup for easy handling.

But let’s close with focus on those advantages and disadvantages.  The barbette allowed the artillery to fire over the parapet and afforded a wide field of fire.  But unlike infantry, the artillery could not simply “duck down” behind the parapet.  And thus were exposed.  What we will look at next is an arrangement that traded field of fire for protection against enemy fire – the embrasure.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 53-4.)

153 years ago today – First shots in a 3500 ton bombardment, 78 week siege of Fort Sumter began

One of the oft overlooked, yet very significant, artifacts in Fort Sumter is a projectile lodged in the interior wall:

Fort Sumter 4 Aug 11 1575

I believe this is a Parrott bolt.  (Though I hope if it is a shell, the projectile was properly disarmed!)  Very likely one of thousands (tens of thousands…) that were fired by Federal batteries on Morris Island, or perhaps the ironclads on station nearby, at Fort Sumter during the long siege of Fort Sumter.

At dawn on August 17, 1863, 153 years ago today,  an 8-inch Parrott rifle on Morris Island fired a shot at dawn on August 17, 1863, 153 years ago today a massive bombardment of Fort Sumter.   Major-General Quincy Gillmore reported over 145 tons of shot, bolt, and shell followed that shot during the next ten days.  The bombardment continued, unrelenting, until September 2.

The objective of the bombardment was to reduce Fort Sumter.  “Reduce” being a military term to indicate the fort’s firepower was reduced, and thus Fort Sumter would not be able to defend itself or interfere with Federal operations.  There are many ways to soft-chew that objective.  At the start of the bombardment, Fort Sumter had 38 large caliber cannon and two mortars.  By September 2, Fort Sumter had but one 32-pdr gun operational, in the northwest casemate covering the harbor side.  So there was some “reduction” accomplished in the conventional military sense of things. But several factors outside the military rule book came into play.  And Fort Sumter remained, even reduced to an “infantry outpost”, a barrier to Federal operations.  Thus the first major bombardment of Fort Sumter resulted in a stalemate.

 

But… this was only the first round.  The bombardment of Fort Sumter resumed in late September with a minor bombardment, with freshly captured batteries on the north end of Morris Island.  And with those new batteries registered, on October 26 the Federals began forty-one days of constant bombardment – day and night.  Throughout 1864, this pattern continued.  Six minor bombardments took place in the winter and spring months of 1864.  One more “major” bombardment blasted the fort from July 7 through September 4, 1864.  And finally, one more minor bombardment, the eighth such, over September 6-18, 1864, represented the last sustained effort to reduce the fort.  And that does not include what Confederate observers called “desultory firing” aimed at Fort Sumter almost every day.

In short, what started on this day in 1863 was for all intents the longest continual battle in the Civil War.   Historian Warren Ripley estimated the combined weight of these bombardments to be in excess of 3,500 tons.  All that in roughly a year and a half of siege operations against a fort of about 2.5 acres in size.*  The effort was at times part of a major push by the Federals to capture Charleston.  Then at others little more than a demonstration to distract from other fronts.  But this siege drug on from August 17, 1863 right up to the fort’s capture on February 18, 1865.

And that storm started on this day in 1863.

Note: By way of comparison, starting on the morning of November 20, 1943 the U.S. Navy fired about 3000 tons of projectiles on the island of Betio, roughly 290 acres, as part of the Battle of Tarawa.  In the span of eighty years, technology increased the size and lethality of artillery.  And at the same time, technology increased the need for such weighty bombardments.

Summary Statement, 1st Quarter, 1863 – Maine’s Batteries

Maine provided seven batteries of field artillery to the Federal war effort.  Of those six were in service during the winter of 1863 (the seventh did not muster until the following winter).  As mentioned for the previous quarter’s returns, we find both numbered and lettered designations for Maine’s batteries.  But I’ll conform to the convention given in the summary.  Of the six batteries to consider, the clerks recorded five returns:

0116_1_Snip_ME

And of those five, we find only two types of cannon:

  • 1st Battery: No return. This battery was assigned to Nineteenth Corps, Department of the Gulf, and had a very active winter operating in Louisiana.  Reports from the department indicate the battery was under Captain E. W. Thompson, with four 6-pdr rifled guns and three 12-pdr howitzers. Lieutenant John E. Morton replaced Thompson early in the spring.
  • 2nd Battery: No location given, but reporting six 3-inch Ordnance rifles. Captain James A. Hall’s battery was assigned to First Corps, Army of the Potomac, in Colonel Charles S. Wainwright’s brigade.  They wintered around near White Oak Church (Fletcher’s Chapel is mentioned).
  • 3rd Battery:  Stationed at Fort [Battery] Jameson, Maryland, but no guns indicated. Captain James G. Swett’s battery was stationed in the Defenses of Washington, in a battery part of the larger Fort Lincoln. The 3rd had a varied history to this point in the war, most recently working with pontoons. Near the close of the quarter the battery became part of the 1st Maine Heavy Artillery (temporarily as Battery M of that regiment).
  • 4th Battery: At Harpers Ferry, Virginia with six 3-inch Ordnance rifles. Captain O’Neil W. Robinson, Jr. commanded this battery, assigned to Kelley’s Division, Eighth Corps, Middle Department.
  • 5th Battery: Reporting at Fletcher’s Chapel, Virginia with six 12-pdr Napoleons.  Captain George F. Leppien commanded this battery, which also fell under Wainwright’s brigade, supporting First Corps.
  • 6th Battery: At Warrenton Junction, Virginia with four 12-pdr Napoleons and two 3-inch Ordnance rifles.  The location is likely reflecting the August 12 reporting date. The battery supported the Twelfth Corps at this time and was posted to Dumfries, Virginia. Lieutenant Edwin B. Dow replaced Captain Freeman McGilvery in command.

So we can fill in some of the blanks and make some minor corrections.  Relatively speaking, the Maine batteries were in order.. from the clerk’s point of view.  Note the artillery assigned to the 9th Maine Infantry dropped from the list for first quarter.

Smoothbore ammunition reported on hand for the quarter:

0118_1_Snip_ME

Two batteries with Napoleons.  And two batteries reporting ammunition for that:

  • 5th Battery: 288 shot, 95 shell, 289 case, and 96 canister for 12-pdr Napoleon.
  • 6th Battery: 192 shot, 64 shell, 149 case, and 64 canister for 12-pdr Napoleon.

Moving to rifled projectiles, the batteries reported healthy quantities of Hotchkiss-patent:

0118_2_Snip_ME

From those reporting:

  • 2nd Battery: 137 canister, 156 percussion shell, 354 fuse shell, and 146 bullet shell Hotchkiss for 3-inch rifle.
  • 4th Battery: 120 canister, 320 fuse shell, and 699 bullet shell Hotchkiss for 3-inch rifle.
  • 6th Battery: 100 canister, 24 percussion shell, 150 fuse shell, and 126 bullet shell Hotchkiss for 3-inch rifle.

No quantities of Dyer’s, James’, or Parrott’s projectiles were on hand.  And just one entry for Schenkl to consider:

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2nd Battery reported 402 Schenkl shells for 3-inch rifle.

Moving to the small arms:

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By battery:

  • 2nd Battery: Sixteen Army revolvers and eleven cavalry sabers.
  • 3rd Battery: 105 Army revolvers and one cavalry saber.
  • 4th Battery: Eighteen Navy revolvers and twenty-three cavalry sabers.
  • 5th Battery: Sixteen Army revolvers and seventeen cavalry sabers.
  • 6th Battery: Seven Army revolvers and twenty-two horse artillery sabers.

It would have been nice if the 1st Battery’s report was here to compare.  But we see 3rd Battery, stationed in the Washington defenses,  likely had a pistol for every man.

Fortification Friday: Building a barbette in a bastion

Last week we discussed placement of artillery in barbettes to form batteries in a fortification defense.  Such an arrangement allowed the cannon to fire over the parapet, even with allowance for declination, at an attacker. Mahan’s description included details about spacing to allow for handling of the gun:

  • Mound of earth 2 feet 9 inches high.
  • Spacing along parapet – 16 ½ to 18 feet of length.
  • Depth of 24 feet (atop the tread of the banquette).
  • Ramp behind the mound at least 10 feet wide, sloped at 1:6 ratio.

Those figures were a rule of thumb to be adjusted to the situation.  And that rule of thumb best fit a situation were several guns were placed on a face, flank, or curtain wall.  In other words, a straight line of the defensive works.

But to illustrate the barbette, Mahan offered this illustration:

PlateIVFig32W

A barbette on a bastion’s salient angle.  Mahan observed:

As barbettes are usually placed in the salients, an arrangement is made for the guns to fire in the direction of the capital.  The construction in this case is somewhat different from the preceding. A pan-coupé of eleven feet is first made; from the foot of the interior slope at the pan-coupé, a distance of twenty-four feet is set off along the capital; at the extremity of this line a perpendicular is drawn to the capital; and five feet are set off on this perpendicular on each side of the capital; from these points, on the perpendicular, a line is drawn perpendicular to each face respectively; the hexagonal figure, thus laid out, is the surface of the barbette for one gun. The ramp in this case is made along the capitol [sic].

Let’s walk through this one step at a time, using Mahan’s illustration.  First we want to setup that pan-coupé within the salient angle:
PlateIVFig32A1

As per Mahan’s guidance, this was eleven feet (indicated in red) perpendicular to the line of the capital (blue line included for reference).

From there, a distance of 24 feet – the depth prescribed for a barbette battery – was walked back towards the gorge:

PlateIVFig32A2

Next, a width of five feet on either side of the capital was set aside within the depth:

PlateIVFig32A3

With the depth and width established, this creates platform for the barbette, marked C on Mahan’s diagram:

PlateIVFig32A4

From there, perpendiculars off each face of the bastion were defined:

PlateIVFig32A5

Now the ramp was defined and laid out.  This would be ten feet wide, 1:6 slope, and along the line of the capital.  This is indicated as “B” on Mahan’s diagram:

PlateIVFig32A6

With the ramp established, all sides of surface of the barbette are defined.  This being a hexagonal shape, indicated as “A” on the diagram:

PlateIVFig32A7

One last bit of work to mention here. The parapet at the salient angle required adjustment to allow the cannon to depress.  Part of the parapet was cut down, indicated as “D” on the diagram:

PlateIVFig32A8

This would cover much of the “sector without fire” at the capital. And it is called the superior slope of the pan-coupé.

Consider these features, the surface of the barbette, ramp, platform, and superior slope of the pan-coupé when seen on the horizontal:

PlateIVFig32A9

This in place, the fortification had a position for one cannon on the bastion’s salient angle. And such could go a long way to reduce that sector without fire.

But one gun?  Just dangling out there over the parapet for the enemy to shoot away?  That won’t do!  So now we should look at arrangements made for several guns within the bastion.  That’s for next week….

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, page 53.)