Author Archives: Craig Swain

Fortification Friday: A Ditch consists of a scarp and counterscarp

It’s Friday, so time for more fort talk.  Let us continue to look at Mahan’s textbook profile and discuss the component architecture:


Last Friday we focused on the Parapet and it’s parts. Time for the Ditch and other structures in front of the fort.  The Ditch served two purposes, as defined by Mahan:

… from its position and proximity to the parapet, subserves the double purpose of increasing the obstacle which the enemy must surmount before reaching the assailed, and of furnishing the earth to form the parapet.

A good Ditch was convenient to the defender and inconvenient to the attacker. The profile of the Ditch introduces several new points and lines to consider:


Points of reference within the Ditch include:

  • G – Crest of the Scarp.
  • H – Foot of the Scarp.
  • I – Foot of the Counterscarp.
  • K – Crest of the Counterscarp.

Working from the last point of the Parapet recall we had the Berm, which was between the Foot of the Exterior Slope (F) and the Crest of the Scarp (G).  The Berm served to shift the weight of the Parapet off the Ditch, but was a necessary weak point in the fortification.

The Ditch itself consisted of three lines. The first was the Scarp, defined as G-H on Mahan’s diagram.   The Scarp is simply “the slope of the ditch next to the parapet….”:


From there, line H-I defines the Bottom of the Ditch:


And lastly line I-K is the Counterscarp, which is simply the opposite side from the Scarp:


A lot of fancy words to describe a hole in the ground, but keep in mind this was the vocabulary used by engineers who were deriving the particulars for structures to achieve specific effects in the field.  To those “specifics,” Mahan wrote:

The ditch should be regulated to furnish the earth for the parapet.  To determine its dimensions, the following points require attention: its depth should not be less than six feet, and its width less than twenty feet, to present a respectable obstacle to the enemy.  It cannot, without convenience, be made deeper than twelve feet; and its greatest width is regulated by the inclination of the superior slope, which, produced, should not pass below the crest of the counterscarp.

So put yourself in the diagram (stick figure if you want).  The average man is under six feet tall.  So a ditch shallower than that depth might allow an attacker to reach over the ditch.  Double that depth is fine, but any deeper would turn a ditch into a mine, and thus require some support beyond what the simple earthwork might provide. Close attention to what is said about the width being restricted by the angle of the Superior Slope.  See the highlighted line:


For the Ditch to work as an obstacle, any defender reaching it should not be able to fire over the Parapet into the fortification.  The line in Mahan’s illustration points to another external feature that we will address shortly – the Glacis.  But where no Glacis existed, the line from the Superior Slope could not exceed the location of the Crest of the Counterscarp (K).

Wait… there’s more.  How about figuring the angle, or slope, at which the sides of the ditch are dug?

The slopes of the scarp and counterscarp will depend upon the nature of the soil, and the action on it of frost and rain.  The scarp is less steep than the counterscarp, because it has to sustain the weight of the parapet.  It is usual to give the slope of the scarp a base equal to two-thirds of the base of the natural slope of a mound of fresh earth whose altitude is equal to the depth of the ditch; the base of the counterscarp slope is made equal to one-half the same base.

Some sandbox physics at play here.  Note there are no slope requirements that apply to the difficulty imposed upon the attacker.  Rather, the main driving factor was to support the parapet.

Mahan would later offer a “mathematical calculation” to cover the required dimensions.  We’ll go over that later… and it requires some focus.  A general rule of thumb, Mahan offered:

On the field a result may be obtained, approximating sufficiently near the truth for practice, by assuming the depth of the ditch and dividing the surface of the profile of the parapet by it to obtain the width.

Furthermore, in regard to all that excavated dirt:

In excavating the ditch it will be found that more earth will be furnished at the salients than is required there for the parapet, and that the re-enterings will not always furnish enough.  On this account, the width of the ditch should not be uniform, but narrower at the salients than their re-enterings.

Since our discussion has focused on the horizontal plain thus far (the profile), there are some terms applying to the vertical plain that we haven’t discussed in detail.  But to water this down, the part of the fort which stuck out from the line would produce more dirt from the ditch than was needed.  So the width of the ditch was scaled in proportion.   The key part in reading that is going back to why the ditch was there – an obstacle which also provided the materials to make the parapet.

So why not build a bigger, wider ditch than required?  Two points I would add here as an “armchair Mahan.”  First, the more dirt the men have to shovel, the less time devoted to other chores.  Labor is a finite resource, and often the main governing resource on the project.

Second, the wider the ditch, the more “bad guys” can stand in the ditch.  If the attacker could mass more troops in the ditch, under the parapet and somewhat protected from direct fires, the “bad guys” might reorganize for a rush.  Again, the width of the ditch had a direct influence on the angle of the Superior Slope, and in that manner it had an overall impact on the size and shape of the Parapet.  A ditch more than twenty feet wide would require many adjustments (some extreme) to the parapet.

This fortification thing requires a lot more thinking than just “grab a shovel and start digging.”  Indeed, things like sine, cosine, and tangent are part of the instructions.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 1-3, 22-3.)


Culpeper Battlefields Park update – gaining acceptance, momentum

Since the start of July, several articles and editorials have appeared in area newspapers in regard to the Culpeper Civil War Battlefield Park proposal.  All voices are positive in regard to the initiative.  The Fredericksburg Free Lance-Star ran an editorial on July 15 which concluded:

At a time when the nation is reassessing how to view and understand the Civil War and its symbols, the stories of sacrifice of American lives cannot be forgotten. Opening historic sites to the public at Brandy Station and Cedar Mountain is the right thing to do.

Just this weekend, the Culpeper Star-Exponent quoted Civil War Trust Policy and Communications Director, Jim Campi:

“If you have a state battlefield park here in the center of Virginia, it would be like Sailor’s Creek on steroids,” Campi said, referring to the battlefield state park in Prince Edward County. “Culpeper really is the epicenter of the Civil War; so much happened here. Even when they weren’t fighting here, they were marching across Culpeper County… all the encampments and the battles. You really can’t tell the story of the Civil War without the story of what happened in Culpeper.”

These are strong statements indicative of the support the idea has received even with the public discussion at an early stage.  For those of us who have carried, for many years, this idea for a Brandy Station and Ceder Mountain park these articles are music to our ears.  Earlier when blogging about having public discussions about a park, I had low expectations.  But the response has exceeded those by yards if not miles.  Furthermore, though I’ve been quiet about this on the blogging side, I find myself every day engaged on the “Culpeper Front” in ways large and small.

When this park comes to be (and I don’t think it is an “if” at this point, but a “when”), we will once again see how public interpretation – specifically markers – have helped build interest, awareness, and support.  Much as the comparison made to Resaca back in May.  (And I would point out the release of the Brandy Station Battle App is a further advancement along that same avenue of approach but in a digital instead of physical format).

Indeed, the Culpeper Battlefields Park, when it comes to fruition, will inherit a wealth of interpretive exhibits, most of which were written by experts on the battle and produced by the professional Virginia Civil War Trails and Civil War Trust teams.  The current interpretive system (including the soon to be in place interpretation on Fleetwood Hill) will cover nearly every need the park might want.  Well, save perhaps a few subjects – such as the USCT crossing at Kelly’s Ford at the start of the Overland Campaign and the passage of Sherman’s troops at the end of the war.  It is a fine system that any park manager would boast of on the first day of operation.

One physical element currently missing, of course, is a formal visitor center.  There are some who have mentioned the use of the Graffiti House as a new park visitor center. That would be a mistake, in my opinion. The house is not in condition to support the foot traffic that will come into the park. It would need extensive, expensive structural work. Nor is it the  place that visitors need to begin their visit (being on the wrong side of the tracks, literally). Furthermore, the real treasure of the Graffiti House is the surviving markings from the war which deserve preservation.  Needed improvements to make a visitor center would detract from that preservation. Unless something akin to what was done for Blenheim in Fairfax – a visitor center  separate from the historic structure – is completed, the graffiti would be at risk.

And such a separate visitor center would essentially mean the Graffiti House would be an exhibit and not the visitor center proper.  At that point, why place a visitor center in a place where visitors will need to traverse a busy highway in order to see what most are looking for? There are many places which could better serve as a temporary visitor center, assuming the state would prefer, as done at other battlefield parks, to build a purpose build visitor center with museum at some point in the future.  Besides, we are getting way ahead of ourselves in planning where to park the buses.

One last point I’d make, which has been voiced in the articles to date is with the operations and maintenance of the proposed park.  As the Culpeper Star-Exponent article this week mentioned, “To expedite the proposal, the [Civil War Trust] is willing to continue to manage the properties for several years after the land transfer, enabling the state to focus its energies and resources on launching the park…”

Some have alluded to the cost of running a new park as a negative in the park effort.  Indeed the Virginia State Park system, as with many across the country, is at best “just” funded in terms of operations budget.  The gracious offer by the Trust will allow some time for the state to work out the particulars to ensure the park is properly staffed and supported.

Although there are a lot of details in the air and a lot of issues to be worked out, the notion of a Culpeper Battlefields Park has gained acceptance and picking up momentum.  The reality of such a park is not far away!

“Forty Rounds of ammunition ought to be enough” – Whittaker on “random fire” and ammunition waste

Last Monday I brought up Alonzo Gray’s discussion of ammunition expenditure by Civil War cavalry.  Gray came to the conclusion that eighty rounds per trooper was sufficient when going into action.  He noted the means of resupply… and difficulty at times of that resupply.  Point being that “80 rounds worth” might be a measure of the time a cavalry formation could maintain a line.

One of the sources Gray cited offered a different count and a very different viewpoint into the discussion.  Frederick Whittaker spent his Civil War a member of the 6th New York Cavalry, going from private to Lieutenant.  And with that came a different perspective from the regimental commanders cited elsewhere in Gray’s discussion. Whittaker wrote Volunteer Cavalry: The Lessons of the Decade in 1871.  While a discussion of cavalry tactics and operations, it drew largely upon personal experiences instead of military manuals.

We can discuss Whittaker in detail on another day.  But for the moment, let us consider his thoughts on ammunition:

But there was one lesson which might have been learned in the war, which yet was not. Neither side seemed to give it a thought; and it was reserved for the sober philosophic German to teach it to us in 1870. This lesson, the most valuable of all, is how to save your ammunition.

General von Moltke, to whose genius the brilliant results of the campaigns of Sadowa and Sedan are owing, is the first man in high place who has had the wisdom to profit by experience in this matter.

The saving of ammunition, if every fully carried out in modern warfare, will be found to be the greatest revolution since Leopold of Dessau introduced the iron ramrod.

The fault of wasting it is the crying sin of modern armies. It is the commonest thing in the world to see officers on the line of battle encouraging their men to waste ammunition.  “Fire away, boys!” “Give ’em hell!” “That’s it!” “Give it to ’em!” is the shout of almost every excited man on the skirmish line; and the officers, having no rifles, do nothing but yell to the men to fire faster.

What is the consequence? Ninety-nine bullets out of a hundred fired in action are fired at random.  A dismounted man goes on the line with twenty rounds in his box, and perhaps forty or sixty more crammed in his pockets. The line fights for an hour and a half; and at the end of that time the cry arises, “Fall back!” “We are out of ammunition!”

Whittaker’s observation is not unique in the annals of military professional writing.  The issue of random fires was the ill from which S.L.A. Marshall formed his premise for Men Against Fire: The Problem of Battle Command.  Set aside for the moment many subsequent professionals who found fault with Marshall’s data, the premise had at least a kernel of truth.  So Whittaker’s complaint carries some weight here.  However, let us be clear that Whittaker and Marshall were set in somewhat different directions to solve this randomness problem.

Whittaker went on to chide the “West Pointers” who would stand behind the line with a saber to lead the men.  He preferred that the officers take up a carbine and share a spot in the line with the men.  Why?  “An officer taking a carbine, and carrying only a few rounds of ammunition, will better realize the necessity of saving it.”

If a prize were offered to the man who should maintain his post on the skirmish line, and bring out by the end of the campaign the largest average number of cartridges in each battle, I am fully convinced that the regiment adopting such a system would kill more enemies and be twice as much dreaded as under the random system.

Sort of counter-intuitive that the unit which shoots the least would inflict the most casualties.  So we might have to reserve judgement there.

If every general officer in our service would enjoin upon his brigadiers to enforce the saving of ammunition upon their different regiments, the gain in efficiency would be enormous.  The moral effect of an army which reserves its fire till sure of its aim is something wonderful, whether in attack of defense; and the corresponding weakness of an enemy which begins to fire at long ranges is equally marked.

If regiments drawing the smallest quantity of ammunition, and still holding their position, were praised in general orders, the emulation would be, we are convinced, productive of unmixed good.  Forty rounds of ammunition ought to be enough for any cavalry skirmisher, if he fights from daylight till dusk; and a regiment announcing itself “out of ammunition” in the thick of a fight ought to be severely censured in brigade, division, and corps orders, even while ammunition was supplied.

That’s fine, but on what experience is this based?  Whittaker continued….

I write from practical experience. I lay on the skirmish line at Cold Harbor in June, 1864, when infantry and cavalry attacked us for several hours.  I knew well that, during all that time, I could not get rid of more than twenty shots, aimed at anything certain.  Bullets were flying about, but they were fired at random. A knot of cool hands lay on the ground near me, each by his little pile of rails; and a shot about once a minute, with a long steady aim at the puffs of the enemy’s smoke, was all we could managed conscientiously.  At the same time a terrible firing was going on at our right, as if a corps of infantry were engaged; and then, the first thing we knew, men were falling back there “out of ammunition.”

Again and again, have I seen the same thing – men reserving their fire, coming to the rescue of the squanderers, to be reproached by those squanderers for having “done nothing, while we were fighting superior numbers.” A beaten man always has an excuse.

But these “out-of-ammunition” fellows have often got better men into grave peril, by falling back, and thus leaving a gap for the enemy to occupy.  I have seen the whole of a brigade forced into a retreat, and the loss of many prisoners, from the failure of a single regiment in this manner.  It was at [Trevilian Station], near Gordonsville, Virginia, we fighting on foot, and before we were aware of it, a force of the enemy was in our rear, and firing into the led horses.  Only the approach of darkness saved many of us, myself in the number, from capture, and I lost my horse and had to foot it until I captured another.

Not that Whittaker carried a grudge against those “out-of-ammunition” fellows, mind you.   Whittaker certainly had a different measure of how long forty rounds would last for those on the battle line.

What would you say to that assessment?

(Citations from Frederick Whittaker, Volunteer Cavalry: The Lessons of the Decade, New York: printed for the author, 1871, pages 19-22.)