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

Consider the cheval-de-bois….

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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.

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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:

PlateIVFig30

“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:

WheelerFig68

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:

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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…

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… 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)

 

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