Fortification Friday: Abattis and Slashings, let us get a clear VIEW these OBSTACLES

Last Friday we considered Abattis (Mahan’s spelling, which I’ll honor in this discussion) and how those obstacles were placed to enhance the defense.  We also considered descriptions offered by Colonel Junius Brutus Wheeler in his 1882 edition of the West Point curriculum on field fortifications.  The material used to construct an abattis was, of course, felled trees.  But we also should considered there were many applications for felled trees beyond just abattis.  This week, let’s look at another section of Wheeler’s instruction:

Slashing. – In compliance with the principle that all houses, trees, brushwood, etc. within range of the work, which could be used as a shelter and a place of concealment by the enemy’s sharpshooters, should be removed, it is essential that the trees within six hundred yards of the work should be cut down.

So we have “slashing” as a verb here… meaning to clear the field of fire and/or field of view. But note that Wheeler does not describe the process of slashing as one designed specifically to create an obstacle.  Thus we have some semantics in play:

As it is not practical to remove immediately the trees from the spot, it is custom to cut them down so that they shall form, while laying on the ground, and obstacle which may be used in the defense of the work.

Trees cut down so as to fall in all directions, form what is known as a slashing.  It is better, where the trees are intended to be used as an obstacle, that they be cut so as to fall towards the enemy; and, in the case of the smaller trees, which might be moved by a few men, the trunks should not be cut entirely through, but only enough to allow the trees to fall.

A thick and well arranged slashing forms an excellent obstruction to an enemy’s free movements. It has the serious defect of being easily burned when dry.

Wheeler offered Figure 72 for this method:


There’s a play of words here, which I will stress.  Slashing, as a verb, was the act of felling the trees for the purpose of improving the field of fire/view from a fortification. The defender may leave those felled trees in place was to create a slashing, used as a noun, that could – stress could – be utilized as an obstacle.

For what it is worth, Mahan did not mention slashings as an obstacle.  But circle back to his discussion of an abattis.  He did offer the defender might “…fell the trees so that their branches will interlace, cutting the trunk in such a way that the tree will hang to the stump by a portion uncut.”  That sounds like, though no figures were offered to illustrate, like Wheeler’s slashing.  However, we must keep in frame Mahan’s definition of the abattis included these instructions, “The smaller branches are chopped off, and the ends, pointed and interlaced with some care, are presented towards the enemy.”  Such implies deliberate preparation of the trees, be those simply felled and left in place… or those moved to a necessary location to create an obstacle.  Wheeler’s description of slashing does not include instructions to clear off smaller branches or leave ends pointed.  And there in lay one difference between an abattis and a slashing (where used as a noun).

Another difference, as we saw above, was the intent of the work.  A commander, if he was using the book definition, would order a slashing (verb) to clear trees at an undesirable location.  He might then order the felled trees left in place, to save labor, which would create a slashing (noun), which simply leave the ground cluttered but not necessarily obstructed.  However, he might order the felled trees arranged to obstruct enemy movements, which Wheeler still called a slashing (noun).  And the commander might order more work to transform those felled trees into what Mahan considered a form of abattis.  You see, by the book the words were used for specific intents.

Oh, but that only applies where the commander knew what the words meant and actually used the words in accordance with the teachings.  How often does that happen?  Well, for the Civil War, perhaps often enough.  First, consider a quote from Major-General John Peck, describing work to be done at Washington, North Carolina, in August 1863 (emphasis mine):

At Washington I examined the old and new lines, both of which are well arranged. The second or interior line has many advantages over the exterior, especially in its command and the requiring of a lesser force for its defense. Some guns should be added, and some slashing done for the better protection of the artillerists against riflemen.

Peck used slashing as a verb here specifically to indicate he recommended moving the tree line back in order to afford a better field of view.  Later, in March 1864, Peck used slashing as a noun when describing works at another point in North Carolina (again, my emphasis here):

The slashing between Fort Jack and the river adds materially to your strength by enabling your flank works to cover that side of the river.

There is no mention of how that slashing might obstruct the Confederates.  The importance of the referenced slashing was to allow the defenders to see the ground and fire upon it.

Later in the war, we see more references to field works and thus slashing (be that as a noun or verb) comes into play more often.  One might say that 1864 was a “golden age” for slashing.  Major-General Quincy Gillmore reported, during the Bermuda Hundred Campaign, on May 21, 1864:

As the woods are now being cut in the ravine on my right, I would recommend not to build the parapet for the 30-pounders until we ascertain the best position for it. The slashing may open out our view considerably.

Slashing, as a noun, to describe an area of felled trees which would be done specifically to clear the view… and allow 30-pdr Parrotts to do what they do so well.  So understanding the difference between a slashing and an abattis provides us some insight into the commander’s intent.

But we find other references where slashings was done with a mind to obstruct. Maybe not the primary purpose, but at least with some intent to obstruct.  Colonel Ario Pardee, in the later stages of the Atlanta Campaign, reported the activity of the 147th Pennsylvania:

Each regiment this day and the days following until the 2d of September were engaged in fortifying their positions and slashing the timber in their front, so as to make the position held by the troops as nearly inaccessible as possible.

Pardee’s intent, apparently, was to create a clear area filled with obstacles in front of his works, thus to make his position “nearly inaccessible as possible.”  Really good obstacles!

I should point out that Peck and Gillmore benefited from a military education.  And Pardee, as best I can tell, learned the trade in the field.  So we should consider that while casting interpretations.  But before we start drawing distinctions here, there’s Brigadier-General John Geary, not a West Pointer but somewhat versed in military affairs, whose writing indicates he knew the difference, describing the activity of his command after the fall of Atlanta:

Our corps, being left to hold Atlanta, we commenced the construction of an inner line of forts and rifle-pits, our camp still remaining near the old outer line, which we had strengthened and improved by slashing and abatis.

Sure, he didn’t like Mahan’s double “t”, but he reported two different types of constructions  – slashings and abattis.  Similarly, Colonel (later Brigadier-General) John Hartranft, with a background in civil engineering but not military engineering, related the activity of his command in July 1864, during the “Fifth Epoch” of the Overland Campaign:

Continued slashing and building abatis until the evening of the 23d, when I was relieved by part of the Tenth Corps.

Here we have two verbs – slashing and building – which indicate the command considered those distinct activities performed during the period.  So knowing the difference between slashings and abattis is important when interpreting a unit’s reported activity.

Though you might be saying that it is a trivial matter to worry if the soldiers cut the trees, then moved them… or just left them hanging from the stumps.  A fair criticism, I concede. Knowing a commander’s intent and the unit’s activity are nice to know, though not always vital in context. But consider the report of Major-General Winfield S. Hancock describing the Confederate positions encountered at Spotsylvania:

 The enemy held a strong line of intrenchments about one-half mile in front of and parallel to the works we had stormed on the 12th. His position was concealed by the forest and protected by heavy slashing and abatis.

Hancock was describing what he was up against.  Those words paint a picture for us, 150 years later, to understand what those Confederate works looked like.  And we have a West Point trained officer, who studied Mahan’s text, clearly indicating there were two sort of obstacles in place that used felled trees.  Thus, by weighing the subtle difference between the two terms, we have a sharper view of just what those obstacles were.  Not only allowing us to share Hancock’s view, but also to consider the level of effort undertaken by the Confederates to construct those defenses.

Now this is not to say everyone who ever used the terms slashing or abattis were employing Mahan’s or Wheeler’s definition of those terms. But it is to say that we should weigh the context of the use of those terms when we encounter them.  As someone famous is reported to have said… a noun is the name of a thing.  It is important, more often than not, that we identify the right thing.

(Citations from Junius B. Wheeler, The Elements of Field Fortifications, New York: D. Van Nostrand, 1882, pages 177-8; OR, Series I, Volume XXIX, Part 2, Serial 49, page 81; Volume XXXIII, Serial 60, page 768;  Volume XXXVI, Part 1, Serial 67, page 338; Volume XXXVI, Part 3, Serial 69, page 69; Volume XXXVIII, Part 2, Serial 73, page 159; .Volume XXXIX, Part 1, Serial 77, pag 668; Volume XL, Part 1, Serial 80, page 578.)


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