The Folwell letters, June 29, 1863: “Co. I is rear guard of the grand army”

On June 28, 1863, Captain William W. Folwell lamented on the wait for the rear guard to cross the bridges at Edwards Ferry, as his command prepared to remove those pontoons.  June 29th found his company BEING the rear guard of the Army of the Potomac.  This was a two letter day for Folwell.  The first was posted in the morning:

Buckeys Town, Md.,

June 29th, 1863, 8 A.M.

Here I am.  Co. I is rear guard of the grand army.  We got to camp at 3 A.M. Got 3 hours good sleep and a good breakfast.  We march to Union Town.  We are well.

Just a short note. But some details that allow us to validate the movements of the engineers.  Aside from the pontoons sent back down the C&O Canal, the remainder of the detachment (parts of the Regulars and the 50th New York Engineers) was sent on a march toward Frederick, Maryland.  The march, which must have begun around mid-day on the 28th, took the detachment of engineers past Poolesville, over the Monocacy, and up to Buckeystown.

And this was the trail end of the Army of the Potomac.

Later in the day, Folwell had time to write another letter home:

Camp Engineer Brigade,

Frederick, Md.,

June 29th 1863.

I wrote you a hasty note in pencil this morning, which I mailed at Buckeystown, while marching hither.  Two miles this side of that place, we came up on the 5th Corps, which followed our trains.  I was then relieved of my duties as Provost Marshall.  I had some very active duty hurrying up some 11th Corps stragglers.  One fellow I had to handle roughly, and finally set two men with fixed bayonets to drive him on.  I was very glad to be relieved. Communication is cut off between us and Washington, the R.R. having been damaged at Mt. Airey Station some miles below here.  I presume, therefore, that said note will be slow in reaching you, as also this is likely to be.  Still, I wish to do all I can to keep you advised of my whereabouts and welfare.  We halted here at noon today, and pitched camp.  In the morning at two o’clock, we march, probably towards [Middleburg], the present H.Q. of the A.P. The news is scarce and uncertain.  Gen. Hooker is relieved and Gen. Meade is in his shoes.  It is said that both Reynolds and Sedgwick declined the appointment.  Co. I is rear guard again tomorrow, and no knapsacks will be carried.  Good Night.

Interesting, if the identification is correct, that Eleventh Corps soldiers would still be straggling on June 29.  That corps had crossed Edwards Ferry first, back on June 25.  There is, of course, a world of possibilities… to include mistaken identification.

I do find interesting that Folwell mentions a break in communications, but no problem with supply or delayed movements.  As I mentioned in the previous installment, Stuart’s cavalry moved through as a fast summer thunderstorm – there and gone.  Of course, Folwell was not getting all the news and knew nothing of the wagon train captured outside of Rockville the previous day.

At the end of the march, the engineers closed on Fifth Corps.  And the anticipated march for the following day was towards the Pipe Creek line. However, while the news of Meade’s assumption of command was correct, the rumors as to alternate commanders was not.

At this stage of the campaign, we leave the operations of the Potomac Crossing and the campaign transitions into the movements that would take the army to Gettysburg.  Folwell’s Company I was not to be in that fight.  Rather, they were placed back with their pontoons.  While not specific to my “lane” on Edwards Ferry, I’ll continue to post Folwell’s letters, so we may hear all of the engineer’s story.

(Citations from William Watts Folwell, Civil War Diary, unpublished, transcription retrieved from University of Minnesota Library, pages 423-24 (pages 429-30 of scanned copy))

The Folwell letters, June 26, 1863, afternoon entry: “It is an old story to see the Army cross”

Looking at the pace, progress of the crossings at Edwards Ferry, the flow of troops on June 25, 1863 was not sufficient given the critical operational situation.  The three corps which crossed that day – the Eleventh, First, and Third, in that order generally – did so with delayed progress.  Not only delays as the engineers placed a second bridge, but the units making the crossing brought their own delays… not the least of which were the additional horses brought by the Eleventh Corps.   And we see the rains, which were recorded by Captain William Folwell’s letter of the day, which caused the Third Corps much misery as the crossing and march into Maryland continued into the early morning hours.

By contrast, June 26 was a flood of men and equipment.  Although on paper, again only three corps crossed – the Twelfth, Fifth, and Second, in that order.  Add to that movement the Artillery Reserve, Army Headquarters element, and the majority of six corps worth of wagon trains.  The march must have seemed endless to any eyewitness.  And Folwell was just such an eyewitness.  Just after noon on June 26, he resumed writing a letter home, this being a post-script to a letter written the previous evening:

P.S.  June 26th, 1863, 1 P.M.

The letter I wrote last evening must lie over till tomorrow as we can only send and receive a mail on alternate days.  We get our mail at present by the little steamer packet which runs on the canal from Georgetown to this place.  To-day we have a fine misty rain, falling steadily, which keeps all of us not on duty under cover.  I have written you a short letter and would have done you a long one if the Major ([E.O.] Beers) and some of the other officers had not come in and spent a large part of the forenoon with me.  The 12th Corps had crossed this morning and the troops of another, (I think the 2nd) have just appeared on the opposite hills.  Gen. Hooker and staff came over just before noon and followed the advance of the Army.  We have yet no information as to the destination of the forces.  Gen. Hooker seemed anxious to have the wagon trains hurried up and commended on of our officers (Capt. [Martin] Van Brocklin) whom he saw moving them on. I have not been out of camp to-day.  It is an old story to see the Army cross, for me.  Bain [Lieutenant Mahlon Bainbridge Folwell] is well and full of business as both adjutant and Quartermaster of detachment.  I hope his troubles are over.  We shall know soon, for Hdqrs. left Washington yesterday and will probably reach here to-morrow.

Though just a brief addendum to the letter, there are many observations which match well into the narrative of the crossing.  The time line given by Folwell is consistent with that of the official reports. The mention of a misty rain is duly noted.  Furthermore, Hooker’s concern, clearly recorded here by Folwell, about the wagons and further delays, should receive a highlight.

On a lower level, we get a small glimpse into engineer operations during a crossing.  There is much “just wait, watch, and stand ready” for them during such a crossing.  As Folwell said, “an old story” by this point in the war.  It is significant that Beers spent time at Folwell’s tent during the morning.  I’ve always felt, based on comments by other officers, Beers was the type of leader to be at the most critical point.  And Folwell’s place, on the Maryland side of the crossing, would be that critical point –  should repairs be needed, another bridge be required, or yet another set of orders come down.

We often associate the C&O Canal with mule-drawn boats.  But steam-powered boats were operated, as the C&O Canal Association reminds us.


Poor Mahalon, though.  His “troubles” were that of additional duties.  Presumably, those would be over when the main body of the 50th New York Engineers moved up from Washington.  A small, personal aspect of the crossing which would probably have escaped record, had we not consulted Folwell’s letters.  Later in the evening, Folwell would start a fresh new letter, offering more observations on a most active day at Edwards Ferry.

(Citations from William Watts Folwell, Civil War Diary, unpublished, transcription retrieved from University of Minnesota Library, pages 420-21 (pages 426-7 of scanned copy))

The Folwell letters, June 17, 1863: Loading pontoons for a trip up the C&O

Last week, I offered a transcription of a letter from Captain William W. Folwell, Company I, 50th New York Engineers, dated June 17, 1863.  We left Folwell as he went about preparing his command for movement from Alexandria across the Potomac (by steamer) to be loaded onto canal boats on the Chesapeake & Ohio Canal.  Folwell’s company was part of a force under Major Ira Spaulding, equipped with pontoon bridges, ordered to Nolan’s Ferry.  With that short introduction, let us turn to Folwell’s lengthy letter for June 18.  Folwell began by describing the activities starting at 9 a.m. the previous day (thus the “discrepancy” in my headline for this post):

On the “Raging Canal”

Near Seneca, Chesapeake and Ohio Canal, June 18th, 1863.

Before I drank the cup of coffee and ate the cookies the men gave me, I thought I was not well. Now, I am all right except that the constant labor and rapid change of scene which we have experienced for the last few days has put me all out of joint.  My mind is in such a state of diffusion that I hardly remember myself. I wrote you a hasty note yesterday morning from Alexandria.  We left there at 9 A.M. on board Steamer “Sylvan Shore.” After putting Gen. Benham’s horses off at 6th St. Wharf, (I saw the place where I bade you and Jennie what I thought to be my last good bye) we proceeded to Georgetown, where we found the Regulars with the train, which we had made up the night before. Disembarked, stacked arms, and went to work at locking our rafts, 4 boats in each., [through the] locks from the river into the canal. Bain [Lieutenant Mahlon Bainbridge Folwell, brother] was unwell and Lt. [Daniel M] Hulse had gone to Washington to get his pay.  I was alone with my Co. and had to work very hard. The men were beset with swarms of women and boys, having pies, cakes, gingerbread and “ice cold lemonade” for sale.  Before we got through, many of them found out the “gin mille” and began to be merry for work. it cost me my most diligent efforts to keep my men together at work.  I am glad that Co.I, although very many of the men drank somewhat, had more but were able to do duty.  Of the regulars, dozens of them lay dead drunk on the boats.  Others were left along the bank.  It was three o’clock when, having been ordered by the Major to bring up the rear, I got my last raft through the locks.  At 4, I got the mules hitched on (3 to each raft) and followed the body of the train.  I don’t think I could be more tired than I was. The day was terribly hot, and we are unused to the close air of cities.  The canal runs right through Georgetown.

This passage is full of the candid observations that attracts us to soldier’s letters.  One can sense the fatigue as Folwell considers the day’s work that hot summer day.  But what stands out most is the “distractions” from work all around the docks.  Again, I would remind readers of the heated inquiries directed towards the engineers during the later half of June.  At Army headquarters, the impression was the engineers were moving slowly and in particular that Benham didn’t have control.  Well… pies, lemonade, and some of that stronger drink will cause some delay!

The particulars here are worthy of pause to consider.  Folwell started boarding transport across the Potomac at nine that morning.  Not until four that afternoon were they ready to move up the canal.  And please note the engineers floated the pontoons in the canal (not shipped inside the canal barges).  Four pontoons were joined to make one raft.  These pontoons were roughly 31 feet long and 5 ½ feet wide.  C&O barges came in several classes, but varied between 50 and 92 feet long, but were usually 14 ½ feet wide.  The latter dimension, determined by the width of the canal’s locks, was the important governing factor. We can, from that, venture educated guesses as to the exact arrangements made to form pontoon rafts.

One last note, Folwell mentions the steamer Sylvan Shore.  She was a sidewheel steamer, reported at 217 tons.  The ship was first chartered by the Army in August 1861.  She operated in North Carolina and Virginia. In fact, just two months earlier, the Sylvan Shore was  involved with operations on the Neuse River.  Milton Martin, who owned the steamer, originally contracted the vessel for $200 per day.  But in May 1863, Army officials altered that deal to $100 per day.  Why do I know so much about this vessel?  Well it was the subject of a post-war court case, in which Martin called for reimbursement at the original, higher rate.  I have not, however, been able to conclusively match the steamer to an image of a similarly named vessel.  (Of note, the orders moving the Spaulding’s engineers mentioned the sidewheel steamer Rockwell.  So at least two steamers were required to move the bridging equipment, men, and animals.)

Those details out of the way, let us continue with Folwell’s eventful cruise up the canal:

The ride up the canal is delightful.  The luxuriance of the hard wood forest, such strong contrast to the barren plains and pines of the “near Falmouth” region.  Before dark, we reached Chain Bridge, which, by the way, is not a chain Bridge, nor even a Suspension Bridge, but a wooden arch truss bridge….


The scenery about it is very romantic.  At sunset, I ordered the Sergeants with their squads to relieve each other during the night in navigating the raft, and unstrapping my blankets, I made a bed on top of some bulks and lay down to sleep.  I had taken a bath in the canal, which disposed me to sleep, and presently I forgot all my cares, and thought no more of them till after daylight this morning. I slept, of course, in my clothes, with a handkerchief tied about my head and a shelter tent spread over me.

As that closed Folwell’s eventful June 17.  For ease of reading, let us stop the transcription here and pick up the rest of the letter in the next post on this thread.

(Citations from William Watts Fowell, Civil War Diary, unpublished, transcription retrieved from University of Minnesota Library, pages 405-6 (pages 411-12 of scanned copy).)

Bridging the Potomac: Diary of William W. Folwell, 50th New York Engineers – Part 1

As a historian, particularly one who’s day job is not history, one of the greatest gifts a friend can offer is a primary source previously not seen or consulted.  Any good historian is always looking for additional sources that may help with the unanswered questions, provide more detail and clarity, or at least offer corroboration for other sources.  History, in my view, is the process of accumulating parts of the story. A process that is never really complete, no matter how authoritative the perception might be.

Last year, John Hennessy shared just such a source in an email titled… as these are apt to be… “Have you seen this?”  The link was to a wartime letters of William Watts Folwell, who served as an engineer officer in the Army of the Potomac for most of the war.  The letters are part of the digital, online collection of University of Minnesota Library.  These appear to be letters home, but have been transcribed into a typewritten page.  Of course, my interest was immediately focused on Folwell’s entries from June 1863 and his accounts of the bridge-laying at Edwards Ferry.

Born in 1833 in Romulus, New York, Folwell attended Hobart College, graduating in 1857.  After a brief position teaching mathematics at the college, he was studying philology in Berlin at the outbreak of the Civil War.  In February 1862, Folwell mustered into the 50th New York Engineers as a first lieutenant in Company G.  He was promoted to Captain in December of that year, commanding Company I.  Then advanced to major in February 1865 (with rank from October 15, 1864).  Some sources indicate he was given a promotion to Lieutenant-Colonel before mustering out in June 1865.  After the war, Folwell briefly lived in Ohio before accepting the position of President, the first president as a matter of fact, of the University of Minnesota in 1869.  And that would be how Folwell’s diary ended up in the university’s collection.


Specific to the Gettysburg Campaign and the movement through Loudoun County in June 1863, Folwell was in command of Company I, 50th New York Engineers.  And that unit was very busy laying bridges that brought the Army of the Potomac from Virginia to Maryland.  As such, I am going to enter his account into my collection of Edwards Ferry resources here on the blog.  Though there are interesting entries from earlier in June (and at other times in the war), for sake of scope, I will start with the entry for June 17, 1863.  At that time, Folwell was in Alexandria:

Bivouac 50th N.Y.V. Engrs., near Alexandria, Va., June 17, ’63, 7 A.M.

Major [Ira] Spaulding takes Cos. C, F and I and one pontoon train to Nolan’s [Noland’s] Ferry on the Upper Potomac.  We are going just at noon as the Steamer comes, and we expect her every moment.  We worked like beavers last night till 2 A.M., making up our train. We had to dismantle the rafts made up at Belle Plain, unload the wagons on those, and then reload the material for shipment by canal.  We take steamer to Georgetown, then enter the canal up which we tow our boats by teams if we can get them; if not, by hand.

Last evening, Capt. Woodward and his wife rode down to camp from their hotel. Bain [Lieutenant Mahlon Bainbridge Folwell, brother]  and I called on them in the evening.  Saw Mrs. Ben. Woodward, also.  Ate sundry and drivers ice-cream and straw-berries, and drank soda waters.

We are both well, barring a slight head-ache Bain has.

I can’t tell you any War news. Don’t know any.  Hooker is probably moving w. between here and the Bull Run Mountain, while Lee goes up the valley.  I wish you could see your husband at this present.  He wears a dirty hat, do. coat, do. vest, do. trousers in the left knee of which is an immense hole through which his drawers display themselves conspicuously. My baggage is over in Maryland somewheres.  When I shall see it, I can’t tell. I have nothing with me but one rubber blanket, one woolen do., one shelter tent, and my sword.

I must try to find an envelope for this before it is too late.  Direct to me as usual.

One detail I must track down is the referenced Captain Woodward.  The meeting with Woodward and his wife seems a pleasant respite from an otherwise hot and dusty campaign.

This account plugs in well with the movements described in the Official Records by way of dispatches.  The bridges had last been used at Aquia Creek.  And at the time of writing, staff officers in the Army of the Potomac were anticipating the need for a bridge over the Potomac at some point near Leesburg. The day before (June 16), Brigadier-General G.K. Warren detailed some of the crossing points on the river between Hancock and Leesburg. Captain Charles Turnbull, of the US Engineer Battalion, had one set of pontoons at Georgetown and was ordered to move up the canal to the Monocacy River on June 17.

On the same day Folwell wrote his letter, Colonel William Pettes, commanding the 50th New York Engineers, received orders from Brigadier-General Henry W. Benham, commander of the Engineer Brigade, to

… detail Major Spaulding, with 200 men from your regiment, to proceed per steamer Rockland to Georgetown, to join the trains which started under Captain Turnbull. The steamer will be at the railroad wharf as soon as possible.  Your men will take four days’ rations with them. The boats, after getting into the canal, will be pushed forward as fast as possible to Noland’s Ferry, where the bridge is ordered to be laid before noon of the 18th.  Teams, if possible, will be procured from Washington, to haul the boats along the canal….

We see, generally, the details of the letter match those of the order.  However, “as soon as possible” was interpreted to allow for ice cream, strawberries, and soda water.

I’ve always found it odd that none of the dispatches or orders issued at this phase of the campaign specify the purpose of the bridges to be laid.  Just a few days after this, on June 19, a clear suggestion came from Major-General Henry Slocum to place a bridge to provide a supply link back to Washington.  And the location for that bridge was Edwards Ferry, where eventually most of the army would cross into Maryland.

But if we walk back to June 17, there is a question as to why the Army of the Potomac wanted a bridge at Noland’s Ferry.  That site is almost fourteen miles upstream from Edwards Ferry, and beyond even White’s Ford.  In my opinion, the most important reason to place a bridge at Noland’s Ferry on the date specified on the orders would be to support movement from Harpers Ferry to Loudoun… emphasis on FROM Harpers Ferry.  As things stood that day, Major-General Joseph Hooker was maneuvering the Army of the Potomac as if to meet the Army of Northern Virginia in the vicinity of the Bull Run Mountains. He had given no indication about movements across the Potomac. But he had asked about the availability of the Harpers Ferry garrison.  Mine is conjecture based on what we surmise of the situation.  But that does open room for logical extensions into the “what if” world.

My plan is to continue transcribing these letters as time permits, with commentary to provide context within the detailed blog posts about the crossing.  It should be “entered into evidence.”

(Citations from William Watts Fowell, Civil War Diary, unpublished, transcription retrieved from University of Minnesota Library, pages 404-5 (pages 410-11 of scanned copy); OR, Series I, Volume 27, Part III, Serial 45, page 179.)

Fortification Friday: Torpedoes – Infernal machines or suitable obstacle?

Last week we discussed mines, with some focus on command detonated mines.  Use of those sort of mines dated back to the invention of gunpowder.  The action of the mine was timed by the defender to effect. If triggered correctly, the mine could disrupt an attack.  Even rumors of mines might even dissuade an attack on a particular sector.  But as we saw there were drawbacks to the use of mine.  (One I neglected to mention was maintenance of the powder charge, which by necessity was often in a place apt to be damp.)  Thus mines were rated as an elaborate, though sometimes worthwhile, obstacle.

It should come as no surprise the Civil War saw the major debut of the automatic mine (we might argue that the “first” were used in the Seminole Wars, though).  Usually called torpedoes in contemporary reports, these differed from the earlier mines by using a trip or trigger acted upon by the attacker.  The torpedoes were set in a manner that an attacker’s footfall or passage would trigger the explosion.  The leader in this field of weaponry was Confederate Brigadier-General Gabriel J. Rains. There were several different fusing mechanisms employed.  I’ll save the technical details for another time (however, for those with an appetite, there is an examination of Confederate torpedoes used on Morris Island in 1863).

Writing for the edification of cadets in the 1880s, Junius B. Wheeler discussed the use of Rains’ “infernal machiens”, …er… torpedoes in the defense:

Torpedoes – Loaded shells buried in the earth just deep enough to be concealed, and arranged so they can be exploded automatically, or at the will of the defense, have been used as obstacles. Arrangements of this kind are known as torpedoes.

The case enclosing the charge may be either of wood or iron. Condemned shells are especially suitable for the purpose.

The explosive compound used to charge them may be powder, gun-cotton, nitro-glycerine, or any material which, upon being fired, will burst the case containing the charge and scatter the fragments in every direction.

The automatic – sometimes known as the “sensitive” torpedo – is fired by contact.  It has the advantage of being exploded at the right time, but has the disadvantages of making the ground, in which it is buried, dangerous to the defense, and of subjecting the men when handling it to the danger of accidental explosions.

The torpedo which is fired “at will” has the disadvantage of being fired oftentimes prematurely, or when it is too late.

Circumstances can only decide as to which of the two is to be preferred as an obstacle.

Wheeler made clear distinction between the command detonated and automatic, or sensitive, mines/torpedoes.  We see a familiar method of employment, being concealed in the earth.

What is not discussed in detail is arrangement of the obstacle.  Wheeler did not discuss seeding roadways or footpaths with these torpedoes.  Instead, at other points in the lesson Wheeler suggests use of torpedoes in the ditch or the ground in front of the works, integrated with other obstacles.  “Torpedoes, military pits, entanglements, etc., may all be combined.”

Wheeler cited a couple of disadvantages to the use of torpedoes.  To that we should add the aforementioned need to protect the powder from dampness.  As the technology evolved through the 19th and 20th centuries, better handling configurations, powder, and triggering mechanisms reduced those disadvantages.  Yet the automatic mine remains an indiscriminate killer on the battlefield to be feared by attacker, defender, and non-combatant alike.

What I do find most interesting is the tone of Wheeler’s instruction.  Gone were mention of “infernal machines” or violations of civilized warfare.  Indeed, the only restraints offered are those practical for the defender.  Fifteen years removed from the Civil War, military leaders accepted the torpedo as a weapon and gone forward to embrace its use.

It would be another century before the Convention on Conventional Weapons, in 1980, would offer limits to the use of anti-personnel mines.  Seventeen years later, the Ottawa Treaty directly banned the use of most types of anti-personnel mines (anti-vehicle and command detonated still being allowed under the treaty).  You see, while the technical evolution of the mine has progressed in a linear form, the acceptance of the weapon has seen rises and falls.

(Citations from Junius B. Wheeler, The Elements of Field Fortifications, New York: D. Van Nostrand, 1882, pages 178-9, 183.)

Fortification Friday: Chevaux-de-Frise, the relocatable obstacle

Consider the cheval-de-bois….


Yes, many a great cavalry trooper started his career atop those trusty steeds.  And how would one’s mother prevent the cavalier’s first charge from taking out the china cabinet?  Well an obstacle of course!  Maybe a table or chair in the doorway… or a nice gate.  But when play time was over, mother would simply move the protective obstacle aside to permit passage.

When the young trooper grew up and took to a taller mount, naturally there were “grown up” obstacles prohibiting his movements to places he should not go.  One of those was the chevaux-de-frise, which we know so well from Civil War era photographs.


We see here two cheval-de-frise (to use the singular form…) in front of works around Atlanta.  Of course by that time of the war the chevaux-de-frise were employed to prohibit infantry charges in addition to cavalry attack.

The “frise” part of the name derives from Frisia, or Friesland, which are low-lying coastal lands along the North Sea, in the Netherlands and Germany.  Residents of that region employed a removable, relocatable obstacle to obstruct cavalry in the 17th and 18th centuries.  And the name stuck.  The important element of the chevaux-de-frise to remember is that removable, relocatable bit.  We’ve discussed abattispalisades, fraises, pickets and stockades that all might work against an attacker.  But those were fixed in the ground. Chevaux-de-frise were not.

Describing chevaux-de-frise, Mahan wrote:

Chevaux-de-frise.  A cheval-de-frise consists of a horizontal piece of scantling of a square, or hexagonal form, termed the body, about nine feet long, which is perforated by holes two inches in diameter, and five inches apart; round staffs, ten feet long, and two inches in diameter, termed lances, shod with iron points, and inserted into the body, so as to project equally from it.  At one end of the body a ring and chain are attached; at the other, a hook and chain; for the purpose of attaching several together, forming a chevaux-de-frise.

We see this illustrated as Figure 30, from Plate IV of the lesson plan:


“A” on the right is the cross-section view.  “B” on the left is the elevation.  Note the chains, as described, on the ends.  Post-war, Junius Wheeler added the chevaux-de-frise could use wire or chains for connections.  His diagram featured a chain snaked around the body:


Perhaps an innovation based on some wartime experience.  But I don’t find documentation to support that conclusion.  Wheeler also noted that British practice was to employ chevaux-de-frise made entirely of iron.  Such would counter the most obvious anti-obstacle tactic – the attacker would need more than axes to clear the iron chevaux-de-frise.

A fine point about the points of the lances, but not mentioned by the instructors, is those building the chevaux-de-frise often dispensed with the specified iron points.  Sharpened points sufficed, as seen in wartime photos.

Mahan continued with some suggestions about construction:

The square is the best form for the body, it requires only five-inch scantling, whereas the hexagon will require twelve-inch timber.

Reflective of that advice, perhaps, we rarely see five-sided chevaux-de-frise in photos.  One other passing note, which Mahan added in his post-war edition, mentioned the use of sword blades as lances, making a “formidable obstacle.”

As for employment, Mahan did downplay the obstacle’s value:

The chevaux-de-frise is not much in use as an obstacle, owing to the difficulty of making it.  It is a good defense against cavalry, and on rock may supply the place of palisades; but even here an abattis would be more effective, and generally more readily formed.

What Mahan did not mention in the instruction is the value imparted by the relocatable nature of the chevaux-de-frise.  There were many places where fixed obstacles were undesirable to the defender.  For instance, roadways or other paths that might be needed for counter-attack.  Furthermore, there were places where obstacles were needed as temporary measures… say only at night.  Recall that was the requirement at Fort Sumter during the long siege.  The Confederate defenders placed chevaux-de-frise during the nights to deter Federal landing parties.  They removed the obstacle before daylight, as the Federal attacks were unlikely during the day and any exposed obstacle would be destroyed by those big Parrotts over on Morris Island.

But look at the chevaux-de-frise employed at Fort Sumter:


These are of a modified form.  The construction resembles a palisading with one set of lances, not four (or five).  These were also braced on the ribands to ensure horizontal orientation over the parapet.  These were relatively light-weight obstructions which could be stored inside the fort during the day and easily set out for the night.

The point being, we may apply the label chevaux-de-frise to any relocatable obstacle.  In fact, the basic function of the chevaux-de-frise remains today in the form of “Jersey barriers” used for base defense at entry points. There are numerous forms of wire obstacles, going by names like “knife rests” and “trestle apron fence”, employing barbed wire or concertina wire instead of the wood lances.  In fact, a coil of concertina wire, if properly staked, serves much the same purpose.  These can be pre-fabricated for quick employment.  And like the chevaux-de-frise of old, can be easily removed when the defender wants to take the offense for a change.

However, I would add the Civil War’s chevaux-de-frise were much “friendlier” in some respects than today’s obstacles…


… particularly if you were a soldier posing for a picture.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 47-8)


Fortification Friday: Trous-de-loup… French for pits in the ground

Trous-de-loup!  Oh-la-la! Anything in French just sounds sweeter… dare I say romantic?


Mahan listed Trous-de-loup as a type of obstacle. What is a Trous-de-loup, anyway?  Um… a straight translation would be something like “holes.”  In the context of military fortifications, Mahan described them as pits, but kept the French nomenclature.  Now these were not just random holes in the ground.  Rather these were fashioned in an orderly manner to serve as an obstacle:

Trous-de-loup. These are pits in the form of an inverted truncated cone, or quadrilateral pyramid; their diameter at top is six feet, their depth six feet, and width at bottom eighteen inches.  A stake is, in some cases, planted firmly in the bottom, its top being sharpened, and the point a few inches below the upper circle.

Mahan offered Figure 28 to illustrate Trous-de-loup:


Let us focus on the left side of Figure 28 for a moment where the pits are demonstrated to the dimensions Mahan specified in the text:


As obstacles go, the Trous-de-loup broke up the ground over which the attacker advanced.  And notice the specified dimensions.  At six foot depth, this ensured the attacker could not gain a lodgement which was not dominated from the defender’s parapets. This pit was dug from the surface level, giving no artificial elevation to aid the attacker. Furthermore, the attacker would have to share the eighteen inch bottom with, if the option were exercised, a post or stake.  Certainly not something an attacker would like to deal with while crossing the “beaten zone” to get at a fortification.

Trous-de-loup are generally placed in three rows, in quincunx order, a few yards in front of the ditch.  They are readily laid out by means of an equilateral triangle, formed of cords, the sides of the triangle being eighteen feet; the angular points mark the center of the pits….

Quincunx order?  Yes, a pattern… arrangement, if you will.  Quick, familiar reference – pick up a six sided dice and look at the five side.  Scott Manning in one of his Wednesday Warpaths will likely point out to us that quincunx is Latin.  It derived from a name for the denomination of Roman currency.  The geometric pattern served as a good arrangement orchards.  And the Roman legions sometimes used it as a tactical formation… but that’s Scott’s shtick.

To illustrate Mahan’s suggested placement of trous-de-loup, let us drop some equilateral triangles on the figure:


Regular placement of obstacles forces the attacker to adopt predictable approach methods. This enables the defender to better place larger weapons… like artillery… to achieve the maximum effective damage.  So don’t scoff at Mahan’s triangles.  There’s a reason for the specification and, in tactical parlance, it rhymes.

With the arrangement set, the digging would commence. And that leads to the question – what to do with the removed dirt?

The earth taken from them is spread over the ground between them, and is formed into hillocks to render the passage between them as difficult as possible.

Looking back at the top portion of the figure, we see that illustrated:


Notice how the “hillocks” would serve to force the attacker to scale more elevation and at the same time put the men above the line of sight from the parapet. So if the enemy stayed in the six foot deep hole, he was exposed to fire from the defender.  And if the attacker attempted to advance through (as in skirting around) these pits, he was silhouetted, exposed, and bunched to the fire of the defender.   The word sometimes used in military discussions is “canalized”, as in redirecting the flow of the enemy’s attack into streams.  I know… a tricky use of the word, but this is the profession that derived the term “uncoilation” to describe movement out of an assembly area….

Continuing with the arrangement of pits, these trous-de-loups get better:

If brush wood, or light hurdles, can be procured, the pits may be made narrower, and covered with the hurdles, over which a layer of earth is spread.

So these might be concealed from the attacker’s view, creating a trap of sorts.

Great, trous-de-loup were formidable obstacles.  But the French is difficult to spell and pronounce.  Writing in the 1880s, Major Junius Brutus Wheeler, who taught engineering at West Point, opted to suppress the French terminology while offering a couple variations of the obstacle type:

Military pits. – Excavations made in the ground, conical or pyramidal in form, with small picket driven into the bottom, are called military pits. (French, trous-de-loup.)

They are of two kinds, viz: deep and shallow.

Describing the deep pits, Wheeler wrote:

Deep military pits should not be less than six feet in depth, so that if they fall into the possession of the enemy, they can not be used against the defense.

They are usually made about six feet in diameter at top, and about one foot at the bottom, and are placed so that the centers shall be about ten feet apart.  They should be placed in rows, at least three in number, the pits being in quincunx order. The earth obtained by the excavation, should be heaped up on the ground between the pits.

The deep military pits match directly to those described by Mahan, save the dimension of the bottom and distance measured between pits.   Wheeler offered this figure to illustrate the deep military pits:


As for shallow military pits:

Shallow pits should not be deeper than about two feet, so that the enemy could not obtain shelter by getting into them.

They should cover the ground in a zig-zag arrangement, the upper bases being made square or rectangular in form, and in contact with each other.  The side of the upper base should be made about equal to the depth of the pit.  The earth obtained from the holes is thrown in front of the arrangement, making a glacis.

Wheeler did not offer an illustration to support this description.  However, we can go back to Mahan where the right side of Figure 28 demonstrates just such an arrangement of shallow pits:

Mahan described these as “small pyramidal pits, with pickets.”  Notice to the right of the illustration we see the glacis described by Wheeler.

Closing the discussion of trous-de-loup… er… pits… Mahan suggested other locations for employment of this obstacle:

Trous-de-loup are sometimes placed in the ditch; in this case, their upper circles touch.

This obstacle is principally serviceable against cavalry.

While these military pits look formidable in the diagrams and seem to be an excellent obstacle, there are considerations governing their employment.  As with all obstacles, the trous-de-loup must be “under the guns”, otherwise the attacker would simply navigate through, perhaps only losing a few steps on the march.  Also consider the time and labor required to place the trous-de-loup.  That’s a lot of earth to displace.  The shape of the pit is somewhat demanding for just shovel and pick.

The trous-de-loup worked best when placed in front of the works in the area cross-fired by flanks.  That ground, presumably already cleared by the defender, might not need much augmentation to deter enemy advances.  So one reason we might not see many trous-de-loup in Civil War fortifications is the engineers weighed the effort against benefit.

In that light, Mahan’s last sentence stands out.  Trous-de-loup was rather effective at breaking up fast moving attacks, such as cavalry.  By the time of the Civil War, direct assault of field formations, much less than field fortifications, with cavalry had fallen out of favor.   With that, the engineers found those pits of less importance.

(Citation from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 44-5; Junius B. Wheeler, The Elements of Field Fortifications, New York: D. Van Nostrand, 1882, pages 176-7.)