Author Archives: Craig Swain

Fortification Friday: The symbiotic relationship between attack and defense

As we leaf through Mahan’s Treatise on Field Fortifications, the lesson plan offered, after defining components of the profile and trace, an important perspective for planning and evaluating fortifications – a connection between the attack and defense of the works:

The attack and defense of intrenchements bear a necessary relation to each other; and it is upon a knowledge of the course pursued by the assailant, that the principles regulating the defense should be founded.

Grant me some license for an analogy here and call this a symbiotic relationship.  Symbiotic, that is, borrowed from biology and defining two organisms of different species that exhibit a long-term, close interaction.  In the case of military affairs, the only reason a place would be defended with earthworks is because the defender feels an attacker might wish to gain possession.  Furthermore, the defender would build the works specifically to counter (if not deter) the most likely form of attack.  Likewise, the attacker would plan the assault based on knowledge of the layout of the defenses.  In short, one plan will exist only because of the other, counter, plan.  Otherwise, there’s simply no reason for the planned action – be that placing a defensive work or organizing an assault of the position.

Mahan elaborated further, providing the students a generalized example of what an attack looked like:

 An attack is, generally, opened by a fire of the enemy’s artillery, whose objective is to silence the fire of the intenchments, and to drive the assailed from the parapet; when this object is attained, a storming party, which usually consists of a detachment of engineer troops, a column of attack, and a reserve, is sent forward, under the fire of the artillery, to the assault. The detachment of engineer troops proceeds the column of attack, and removes all obstacles that obstruct its passage into the ditch. The line of march is directed upon a salient, through a sector without fire, and on the prolongation of the capital, as this line is least exposed to the fire of the works.

Depicting that approach on Mahan’s figure:


See how this approach was designed to take advantage of an inherent flaw of the works? Mahan continued with more exploitation of the fortification flaws:

When the ditch is gained, the party makes its way to a re-entering angle, where, sheltered from the fire of the flanks, the work is entered by the column of attack, either by making a breach in the parapet, or else by means of ladders.  The reserve supports the column of attack in case of need; and if it is driven from the works, covers its retreat.

Again, as that would look on Mahan’s figure:


This approach allowed the attacker to pick apart the defense by working under the parapet within the ditch inside the dead space, avoiding the angles of defense.

So how does that look from the defenders side?

The manner of making the defense is with artillery, musketry, the bayonet, and sorties.  The enemy is attained at a distance by the fire of the artillery and musketry, whose effect will chiefly depend upon the length of time that he is kept exposed to it by the ditch, and the obstacles in front of it. The bayonet is resorted to, as soon as the enemy shows himself on the berm; and sorties are made, either when any irresolution or confusion is seen in the enemy’s ranks, or at the moment he is repulsed from the parapet.

Note that Mahan didn’t emphasize here the nature of the parapets, faces, and flanks in order to build the perfect defensive line.  That technical perspective he saved for a more detailed explanation.  Instead he focused on what the defender could do with their weapons.  Implied in the notion of the sortie is that the defender retained high motivation to conduct such a counter-attack.  And with that, Mahan is admitting that flaws would be present in any defense.  To mitigate those flaws, where existing, the defender applied cold steel, hot lead, flesh, and bone.

But you see here how the nature of attack and defense fit against each other.  The attack had to be planned with a mind to exploit the flaws of the defense.  The defense had to be planned to minimize those flaws.  After establishing that symbiotic relationship, Mahan proceeded to lay out nine principles of the defense – some technical, others tactical, and yet others addressing the “spirit” of the defenders.  We’ll take a look at those next week.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 5-6.)

Cavalry tactics: What of the lance? “Americans do not take kindly to the lance.”

Many years ago, when comparing the 19th century American cavalry experience with that of the European powers, a Anglophile friend remarked that, “Americans just didn’t seem to understand the usefulness of the lance.”   From the European perspective, the lance was frequently issued and employed.  The narratives of post-Napoleonic battles and campaigns include frequent mention of lancers employed to great shock effect at key points of the field.  So we have images such as this one, depicting the charge of Polish Uhlans at the city of Poznań during the November Uprising 1831, showing the Europeans’ use of the lance.

On this side of the Atlantic, we have scant few contemporary illustrations of the lancers in action.  In the manuals of the era, American writers gave space to the lance – as part of both dismounted and mounted drill.


But that was, as one might say, the long and the short of it.  A few pages devoted to drill instructions, and not a lot said about tactical employment.  The American experience with the lance is mostly on the receiving end rather than being one employing it.  In his Cavalry Tactics, Alonzo Gray cited Major Albert G. Brackett’s History of the U.S. Cavalry in that regard, speaking of the battle of Buena Vista, February 23, 1847:

The cavalry made one most gallant charge against the enemy on the 23d of February, and cut their way through them; but the Mexican lancers were far from being a contemptible enemy, and many of them were admirable horsemen. Our people had the advantage of larger horses and heavier men as a general thing, but the Mexicans were much more agile, and could handle their horses as well perhaps as any people on earth.  With the lance they were greatly our superiors, and used that weapon with great effect both at Buena Vista and at San Pascual.

Gray might also have mentioned the actions of the Californios at Los Angeles during the same war.  In that case, a less well-trained and organized force of lancers drove back US Marines acting as infantry.

The Mexican lancers were perhaps the closest to those colorful European lancers that the Americans ever faced.  But on the opposite end of the spectrum, the U.S. cavalry frequently encountered the lance in operations against the natives on the plains.  So the American focus on the lance tended to be how best to counter the lance.  Philip St. George Cooke made note of this in his Cavalry Tactics manual of 1861:

The attack or defense against the lance (it is the common weapon of the mounted Indians) depends much upon horsemanship, and judgement of the rider.  It is parried like the sword; and you must press in at your opportunity to close upon the antagonist. You must invariably endeavor to gain his right rear when he is least able to attack or defend; the left rear and left, weakest for the sabre, are the strongest positions for the lance; the same may be said of the bow and arrow; in pursuit always approach at the right rear.

Reading that section, I get the impression Cooke was writing with some knowledge on how best to run down a “lancer.”

Moving forward to the Civil War, Gray mentioned the use of the lance by the 6th Pennsylvania Cavalry, known as Rush’s Lancers.  That unit’s wartime story is well documented.  Although carrying the lances into 1863, by the Battle of Brandy Station and their famous charge upon Confederate positions on St. James Plateau the regiment was “conventionally” armed… in the sense of conventional American cavalry.

There were other lesser known lance equipped units during the war on both sides.  But none of these had a battlefield impact.  Instead, Federal and Confederate cavalry went into action with saber, pistol, and some form of long weapon – chiefly the carbine.  Gray cites Brackett’s conclusion in this regard:

We have yet to make good lancers in the United States, as experiments, even on a small scale have proved failures among the Americans.

Gray adds in his notes, “Americans do not take kindly to the lance.”

Why would the lance be so useful for the Europeans (and Mexicans and Native Americans), yet be totally useless in the hands of American troopers?  Addressing that, Gray first pointed out differences in terrain, “The lance cannot be used to advantage in a close wooded country such as is found everywhere along the Atlantic coast.”  That might easily be countered by pointing out that most battles in the Eastern Theater, outside of Spotsylvania County, Virginia, were fought in open, farmed terrain.  One must assume Gray was voicing the underlying reasons why earlier generations of American cavarlymen had not taken to the lance, and not limiting his response to the Civil War.

From there, Gray offers what I think is the practical response to the question – the growing obsolescence of the lance when opposed by rifled carbines:

In meeting an enemy armed with the lance it would be necessary to first break the continuity of his lines before the saber could gain a superiority.  In these extracts there can be found many examples where cavalry charges have been broken by magazine fire by holding it till the charging line is within very close range.  The traditions of our cavalry and its training are such that we can dismount and fight on foot in a very short time.  This dismounted fire should be supported by mounted troops, which should deliver the charge as soon as the lancer line is broken.

Thus Gray felt the American emphasis on dismounted fighting played to advantage over the lance.   He offered two other responses, given scenarios with more demanding details:

If it were necessary to meet lancers, whose lines were unbroken by fire action, with shock action of troops armed with the saber, I would endeavor to strike the weakest point of their line with a mass formation of some kind, either by squadrons in column of troops or in line of troops in columns of fours. Thin lines fleeing in front of lancers would soon cause their lines to become so broken that other troops held in reserve could meet them with a fair chance of success.

In other words, the power of the lancer formation was in close order mass.  Anything done to break up the formation, even be that the sacrifice of a troop or squadron, would reduce the impact of the lancer formation.

The obvious point, to turn a pun, about the lance was the inadequacy of the weapon when employed on a battlefield with rapid firing (relatively speaking) firearms.  Yet, 100 years ago cavalry of all the great powers of Europe carried steel lances into the first campaigns of World War I.  The Polish cavalry, descendants of those Uhlans of 1831, were still training with the lance on the eve of World War II.  Once a military formation picked up the lance, it seemed hard to put it down.

(Citations from Alonzo Gray, Cavalry Tactics, as Illustrated by the War of the Rebellion, Fort Leavenworth, Kansas: U.S. Cavalry Association, 1910, pages 26-28; Albert G. Brackett, History of the U.S. Cavalry, New York: Harper & Brothers, 1865, pages 83-4; Philip St. George Cooke, Cavalry Tactics or Regulations for the Instruction, Formations, and Movements of the Cavalry, Volume 1, Washington: Government Printing Office, 1861, pages 64-5.)

Fortification Friday: Dead space is a dangerous angle for the defender

Last week we looked at faces, flanks, and curtains of a fortification.  And with that discussion, we began to look at the geometry outside the fort which depicted the areas covered by the defenders.  In particular, we saw how Mahan demonstrated the angle of the salient within the plan:


For any given salient angle, there is a line to depict the orientation of the salient.  This line ran through the point where the faces intersected, and perfectly split the angle… or as Mahan described:

The line bisecting a salient angle is denominated the capital.

We see two capitals in Mahan’s textbook diagram:


The point at which the capital crossed the line of the fortification was an important feature.  That intersection determined the forward-most defensive point on the salient.  Taken in conjunction with the complementing salients (to the left and right), this set a forward-facing imaginary line (outside the physical lines of fortifications, that is).  Mahan gave this a name and definition:

… the distance from a salient to its opposite flank is a line of defense.

Here is that line on the diagram:


Note that the line of defense is in this case parallel to the curtain.  That was not always the case, as situations might demand asymmetrical salients.  But going back to the nature of the layout with salients, angle of defense, and other components in order, the line of defense was in front of the curtain.  In short, the line of defense depicted the line on which the defender hoped to resist the advance of the attacker.  Consider how the two angles of defense served to provide a cross fire across that line:


Yes, a practical application of geometry there.

While that is fine to show where the defenders would shoot at the “bad guys.”  There had to be a converse to that aspect of the defense – the places where the defenders could not engage the “bad guys.”  In other words the natural defects of a defense:

The form of the parapet, and the direction in which a soldier naturally aims in firing over one, are the causes of two of the most important defects of intrenchments.  Owing to the form of the parapet and its height, the fire can take effect only at some distance beyond it, so that when the enemy has approached very near the parapet, particularly when he is in the ditch, the fire will pass over his head, unless the flanks are so arranged that their fire will sweep every point of the ditch; an arrangement of which particular angular systems are alone susceptible.  This space, where the enemy can find a shelter, is, generally, in the ditches at the re-entering angles.   It is denominated a dead space, or dead angle.

We discussed one aspect of this in relation to the planing of the profile:


But now we are matching that in with the layout on the horizontal plane.  Let me depict that on Mahan’s diagram:


Consider the play of the two causes cited by Mahan here.  Because the defender on a given face cannot aim below the crest of the parapet, he cannot engage an enemy in the ditch to his front.  And this space just happens to be outside of the area covered by the opposite face’s angle of defense. This meant the ditch directly in front of a face along with the ditch along a curtain were within the defined dead space.  This is depicted with the red shaded line, in the figure above.  To mitigate the dead space allowed by the works, the engineer had to carefully arrange the salients with respect to the curtain, thus minimizing the dead space encountered at the re-entering angles.

But that was not the only dead space to consider.  Mahan noted another issue related to the orientation of the faces:

In delivering his fire a soldier usually aims directly to the front, so that the line of fire and the parapet make nearly a right angle with each other.  In consequence of this the salients receive no protection from themselves, and there is angular space in front of each of them (which is equal to the supplement of the salient angle) that is defended only by the fire of flanks.  This space is denominated a sector without fire.

Going again to the diagram, here are sectors without fire:


Note how the capital line also bisected the sector without fire.  It’s a geometry thing again, and a good reference line.  This flaw was not quite so bad as dead space, since the complementing salients had the area under the angle of defense… though at longer range.

What should be apparent in this discussion is how important the measure of those angles were for the arrangement of defense.  If any of these angles were too extreme (too wide, or too narrow) that would introduce demands on the adjacent sectors of the defense.  If those demands were not provided for – mitigating the natural flaws of the defense – then the works were compromised.

While it is easy to sit down with a blank sheet of paper and draw out a defensive arrangement which avoids those extremes, maps of the actual ground to be defended are not blank sheets.  Variations in elevation, watercourses, foliage, buildings, and other features factored into the plan.  You see, this was not a simple exercise in geometry.  That’s why Mahan called the subject he taught “Military Science,” don’t you know!

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 4-5.)