Mahan on Artillery Tactics, Part 4: More on the Defense

Let us continue the discussion of artillery as used on the defense, according to Mahan. And we again turn to Chapter II, verse 151…..

Those positions for batteries should be avoided from which the shot must pass over other troops, to attain the enemy. And those should be sought for from which a fire can be maintained until the enemy has approached even within good musket-range of them.

Outpost, 60-1.

Common sense at play here. Fuses are not fail-proof, no matter how good the quality control is at the arsenal. Short rounds were a concern then as they are today. A further concern was the ballistic path of the sabot used behind many projectiles. Though made of wood, that could still injure or kill. With the introduction of rifled guns, another concern entered play – the lead or soft iron sabots often sheered off after the projectile left the muzzle. Those fragments took less predictable paths.

The other part of this is the desired effect of allowing the cannon to engage right up to… and inside of… musket range. The “skirmisher” community will note that Mahan was writing this passage before the rifled-musket was in widespread use. However, we should note that well into the Civil War, 100 yards was still considered the effective range of those rifled-muskets, as the practitioners were focused on volley fire effects as opposed to the effective range of individual weapons.

Where the wings of a position are weak, batteries of the heaviest caliber should be placed to secure them.

Outpost, 61.

Another sensible suggestion here. But one that must play with earlier passages that dictated the bigger caliber pieces be placed on “the more retired points” as opposed to advanced positions. Looking back at the “taking away a course of action from the enemy” mindset, those batteries assigned to support the flanks would be there to remove an option to attack on a flank. Such implies, generally speaking, that in the defense the flanks should be tucked in or refused. I would not argue against that as a general application, but certainly not submit flanks should always be refused. Given terrain or other factors, one might extend a flank position to cover the front of the main defensive line…. you know… like in those simple entrenchments that Mahan wrote of in other volumes.

Thus far, Mahan has placed the light batteries (shall we say the “mounted” batteries?) and the heavy (or “foot”) batteries. What about the horse artillery?

A sufficient number of pieces – selecting for the object in view horse-artillery in preference to any other – should be held in reserve for a moment of need; to be thrown upon any point where the enemy’s progress threatens danger; or to be used in a covering the retreat.

Outpost, 61.

Stomp your feet here to ensure all the cavalrymen hear and heed this. Horse artillery, in the defensive, was not simply attached to the cavalry for support of the troopers doing what ever it is they do on the defensive. Instead, the horse artillery was a reserve force to be used when pressed. If we turn again to “taking away courses of action” then here we are considering how an enemy commander would follow up behind initial success. If that assault has indeed achieved a lodgement on the main defensive line, the next step would involve pressing reinforcements forward to enlarge gains and break the line. The counter, Mahan proposes here, is the rapid, flying batteries of horse artillery introduced to seal that fissure.

And if that cannot be attained, at least have those horse artillery batteries in position to dissuade the enemy from following up with a close pursuit. A handful of well placed shells from the horse artillery should at least cause pause.

Everything thus far we might summarize as “use common sense and good judgement.” But the next paragraph is where the armchair generals will set up and start typing comments….

The collection of a large number of pieces in a single battery, is a dangerous arrangement; particularly at the onset of an engagement. The exposure of so many guns together might present a strong inducement to the enemy to make an effort to carry the battery; a feat the more likely to succeed, as it is difficult either to withdraw the guns, or change their position promptly, after their fire is opened; and one which, if successful, might entail a fatal disaster on the assailed, from the loss of so many pieces at once.

Outpost, 61.

Yes, at first glance, Mahan is laying out an argument against massing artillery on the battlefield. And our latter-day Stonewall Jacksons are quick to point out massed artillery is often the key to victory!

The important part of this passage is “large number of pieces in a single battery.” This is a “battery” not as an organizational unit, but as a position. Reading as such, this is a warning about putting multiple batteries in one contiguous position. If those guns are not arrayed as discussed at earlier points in this discussion of artillery on defense, then such a collection would be a vulnerable, tempting target. Placing the guns hub to hub is not “massing the guns.” But arranging those guns, in accordance to the guides presented by Mahan, is.

What I’d contend is that Mahan was not arguing against what Henry Hunt would do at Malvern Hill. Just the opposite. Prior to July 1, 1862, Hunt organized and emplaced the artillery into a fine example of what Mahan encouraged through these couple of pages on defensive arrangements. Go through the checklist – good engagement ranges, cleared fields of fire, complementing postings, light batteries advanced, heavy batteries retired, wings protected, infantry kept clear of the guns, and all well supported. And that arrangement allowed Hunt to introduce fresh batteries and withdraw tired ones, with relative ease. Thus, what Hunt had at Malvern Hill was not a “large number of pieces in a single battery” but instead a massing of combat power on a good position which maximized the capabilities of the artillery. Famously, one year and two days later, Hunt will accomplish the same feat on another battlefield while defending Cemetery Ridge. We might easily turn to the other side of the war and point to good use of massed artillery at Fredericksburg.

I think what Mahan is arguing against in this passage is actually instances like Missionary Ridge. One might say the Confederate artillery positions on that ridge were well placed for a siege in which their fire would be focused on distant Federal lines. The problem was no proper adjustment was made when that position transformed, due to the shifting of tactical situations, to a defensive one. And so that checklist that Hunt met on those hot July days was not met on that autumn day outside Chattanooga – dead space under the guns even past musket range, no complementary postings, no advanced or retired positions, infantry lines interspersed with the artillery, and little room to move the batteries around. And if we circle back to the “taking away a course of action from the enemy” notion here, I’d posit this counter-intuitive thought with a wry smile: the position on Missionary Ridge was so bad that it invited Federal commanders to accept and pursue a direct assault as a course of action. And as a demonstration, at that!

The last paragraph in this section on defensive arrangements for artillery strikes to the logistics of keeping those guns feed:

In all defensive dispositions the ammunition should be most carefully husbanded. A fire should never be opened until the enemy is within good range; and, when once opened, be continued with perseverance and coolness up to the last moment in which it can be made effective.

Outpost, 61.

I’ve mentioned this a time or two before, expressed as “staying power” of the guns. By this I mean the time for which the gun can remain at a position and actively part of the battle before having to replenish ammunition. Obviously many factors come into play here. Not the least of which is the number of rounds in the ammunition chests (in other words, the smaller-bore weapons had more rounds to shoot, all things being equal… yet another reason to have those big guns at retired positions). As we alluded to above (and at other places on this blog), Hunt and other good artillery commanders mitigated this with a good system to rotate batteries in and out of the line. Hunt also devised a very healthy system to push full ammunition chests up to the points where needed. Such adds another requirement here to those “good position” checklists, in that we must also consider allocating space to allow all the traffic needed in order to maintain a position “up to the last moment.”

And I stress “staying power” over perhaps the cyclic rate of fire. More so than simple weight of metal, it was the paced, deliberate, and measured fire which was desired. So let’s cast off these notions that artillery was just there to belch out canister, send smoke into the air, and make a lot of noise. The impact of those big guns, particularly on the defense, was to shape the flow of the battle… taking away courses of action available to the enemy.

(Citations from Dennis Hart Mahan, An Elementary Treatise on Advanced-guard, Out-post, and Detachment Service of Troops, and the Manner of Posting and Handling Them in Presence of an Enemy, New York: John Wiley, 1861, pages 60-1.)

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Mahan on Artillery Tactics, Part 3: In Defense, artillery is the “principal part”

I started the examination of Dennis H. Mahan and artillery tactics earlier this year with an introduction and a word about the “place” of artillery. That latter referring to what artillery was supposed to do on the battlefield… not the physical place. Now resuming that conversation, let’s move from the somewhat theoretical side into how those ideas would be applied… again, according to Mahan. And that takes us from the “place” as in the role or occupation of artillery more towards “place” as in the actual position relative to the other branches. We start with the general guideline for placing artillery:

The manner of placing artillery and its employment must be regulated by its relative importance under given circumstances, with respect to the action of the other arms.

In the defensive, the principal part is usually assigned to the artillery; and the position taken up by the other arms will, therefore, be subordinate to those of this arm. In offensive movements the reverse is generally obtain[ed].

Outpost, pages 59-60.

Even the most pedestrian, non-tactical study of the Civil War battlefield reinforces this notion. But there is a pitfall here that some novices will fall into. This is not to say that artillery’s importance was weighed to the defense, and was simply an add-on for the offense. Rather, what Mahan indicates here is that the defense, if properly organized, will center upon and be dependent upon the artillery for its strength. While the offensive arrangements would place emphasis on the “moving parts” with the artillery arranged best to support that component. In either case, the artillery placement requires just as much thought. It is simply a matter of which component the commander needs to carry the battle…. or… “relative importance under given circumstances.”

With the central role of artillery in the defense at the fore, Mahan then spoke to how those guns should be arranged:

In defensive positions the security of the batteries is of the last importance. Unless the batteries are on points which are inaccessible to the enemy’s cavalry and infantry, they must be placed under the protection of the other troops, and be outflanked by them.

Outpost, 60

By “last importance“, I believe Mahan was saying the defender should not avoid placing guns on less than idea terrain. The guns should be placed where their firepower would best achieve the mission of the defender. After all, those other arms were there to prevent a battery from being exposed… or at least supposed to be there.

As in the defensive, we should be prepared to receive the enemy on every point; the batteries must be distributed along the entire front of the position occupied, and on those points from which they can obtain a good sweep over the avenues of approach to it; the guns being masked, when the ground favors, from the enemy’s view, until the proper moment arrives for opening their fire.

Outpost, 60

Finally, we are pointing to the places to drop trail! The point I would emphasize here is this notion of masking batteries. In 1861, “masked batteries” were somewhat a boogie man, particularly on the Federal side. The very nature of selecting a good position should bring the officer to place artillery in masking positions. In effect all good artillery positions should be masked. But in reality, when those commanders of 1861 were writing about their fears of “masked batteries” they were referring to positions where their columns might be surprised or ambushed by the waiting enemy using concealed cannon. But before we go down the route of saying all good artillery positions were ambushes and such, we’ve got to take a step back and recognize the same word was being used with different intents.

Mahan’s masked batteries were not necessarily in unseen places. Rather, they were in places where anything which could be seen was within engagment range. Given the range of a 6-pdr field gun (the standard light piece at the time Mahan was writing), that translates out to 1,500 yards, or 0.85ths of a mile…. fine, round it to a mile. That’s a lot of space to work with. And given the average human’s perceptions at the range of a mile, that does not need to imply the battery is camouflaged or excessively concealed. We might double that “round about a mile” space when taking into account rifled artillery. But that’s about as far as I’d take it… range, in the Civil War context, had much dependency on target acquisition.

Taking in mind my interpretation of artillery’s role on the battle – “to take away or deny the enemy a course of action” – then we can start quantifying the value of a defensive position based on how much of that rounded up to a mile range the gunner can see when looking over the breech. Does it give full visibility of everything out to a mile? Give it a score of 100. Is there a rise or depression that prevents engagements at less than a mile? Start taking points off. That gives some measure of how artillery might influence the battle… or not… from a particular point.

Mahan continued with details about placing the trails of those cannon:

The distance between the batteries should not be much over 600 paces; so that by their fire they may cover well the ground intervening between them, and afford mutual support; the light guns being placed on the more salient points of the front, from their shorter range and greater facility of maneuvering; the heavier guns on the more retired points. Guns of various caliber should not be placed in the same battery. A sufficient interval should also be left between batteries of different caliber; to prevent the enemy from judging, by the variations in the effect of the shot, of the weight of metal in the batteries.

Outpost, 60

This paragraph lands at the intersection of technological development and doctrinal evolution. First let’s look at that distance between batteries. The Army (modern version.. but I submit this would be timeless) taught me that an average person’s “pace” is 30 inches… or 0.83ths of a yard. And 600 paces thus works out to 500 yards. ( 600 x 0.83 = 500…. don’t you like how the professor turned that into clean numbers?) That 500 yards is roughly a third the range of a 6-pdr field gun firing solid shot. And 500 yards is roughly half the range of a 12-pdr field howitzer. Thus, if the 600 paces rule is adhered to, even the smallest, lest powerful field pieces could easily support adjacent batteries.

Not much to expand upon with regard to placing those smaller pieces out front. That speaks of common sense. We’ll get into discussions of horse artillery and building a mobile reserve later.

But it’s this warning about mixed batteries which cuts across some of the doctrine in place when Mahan was writing. From the earliest times, the Army’s practice leaned toward mixed batteries. Even up to the writing of the 1860 tactics manual, the Army’s standard arrangement were batteries with two sections of field guns and one of howitzers. That applied for both light (6-pdr field gun / 12-pdr field howitzers) and heavy (12-pdr field guns / 24- or 32-pdr field howitzers). Yet, we know that early in the war senior artillerists advocated for uniform batteries. Mahan gives us a good tactical justification for uniform batteries. And we know Barry and Hunt would weigh in on this during the war years. I think the persistence of the mixed battery on the tables of organization has more to do with forces outside the artillery arm – namely the Ordnance Branch and the other two combat arms branches – and their perceptions of what the artillery needed in order to accomplish a mission. Not as acute, but along the same lines as the internal debate over tank destroyer types as the same US Army rushed into action during World War II.

These notions in mind to answer the question about where to place the artillery in the defensive, let’s circle back to this “taking away a course of action from the enemy” thing I keep talking about. If a defense, featuring artillery, is laid out in accordance to the principles Mahan stated in these paragraphs (and, if time permitted, placed in some of those fortifications, that we’ve discussed at length in the past) then the enemy would find a killing field that he would not be anxious to cross. The direct frontal assault, which is always the easiest and most efficient maneuver for an attacker to perform, would be off the table. Or at least should be off the list of options. We well know of many instances where a commander did not… and his men paid the price. But let’s save the discussion dynamic and flexible leadership for another day….

(Citations from Dennis Hart Mahan, An Elementary Treatise on Advanced-guard, Out-post, and Detachment Service of Troops, and the Manner of Posting and Handling Them in Presence of an Enemy, New York: John Wiley, 1861, pages 59-60.)

Mahan on Artillery Tactics, Part 2: The “Place” of Artillery

Let us continue focused on this discussion of Dennis H. Mahan’s thoughts of artillery tactics, in the pre-Civil War context. In the previous post, we noted some of the context to the label of “tactics” in the Civil War-era manuals. But the key point was what Mahan called the duties of artillery – “… to support and cover the other arms; keep the enemy from approaching too near; hold him in check when he advances; and prevent him from debouching at particular points. ”

I offer a 21st Century sound-byte worthy summary of this as – to deny the enemy commander a course of action. And correspondingly, that would grant the friendly commander a different set of options. That’s my interpretation. So feel free to disagree, and drop a comment. To me, Mahan’s duties boil down to the use of artillery in a way that prevents the enemy from using particular pieces of terrain (in defense), opting to attack by way of a particular approach (in offense), or at least keeping the enemy at greater than musket range. Perhaps another way of putting it – forcing the enemy commander to adopt something other than the simple, apparent plan of action. (And with a complex plan adopted… the enemy commander leaves himself open to all sorts of criticism from later day historians who shall question his ability!)

Mahan continues on, later in his opening chapter, to describe the place of artillery on the battlefield, in his estimation. Initially he described the metaphorical place on the battlefield:

The artillery, which had for a long period, and even still, preserves the character of eminent respectability, has of late years begun to infuse a dash of the dare-devil spirit of the cavalier into its ranks. If it has not yet taken to charging literally, it has, on some recent occasions in our service, shown a well-considered recklessness of obstacles and dangers, fully borne out by justly deserved success.

Some will read this passage and begin shouting about the artillery charge and such. Not even close! Rather what Mahan is suggesting is that artillerymen of his time (the 1840s) were inclined to more aggressive placement on the battlefield, not simply running up within musket range to trade blows with the infantry. So what was that aggressive placement?

Well to start with, Mahan points out that artillery conformed to classifications – heavy and light (with divisions for foot and horse artillery) – each of which had places tailored to their strengths and weaknesses. Heavy artillery, which he categorized as 12-pdr caliber and above, was reserved for batteries of position and “is seldom shifted during the action” Light artillery, being 6-pdr gun and 24-pdr howitzers (!), included foot artillery and horse artillery. Foot artillery being those batteries with the standard allocation of horses, and which the crews marched alongside (usually). Horse artillery, of course, received sufficient animals to allow the crews to ride, and were thus more quickly moved on the field. Both were to “follow the movements of the other arms.”

However, as we well know, those classifications were soon blurred by technological advances – notably “light” 12-pdr guns and rifled artillery. And such brings to mind the “chicken or the egg” debate as to the technological advances driving tactical innovations, or vice-versa. I think Mahan argued “both”:

Improvements both in the materiel and the tactics of artillery have been very marked within late years. Formerly, considered only in the light of an auxiliary on the battle-field, artillery now aspires, and with indisputable claims, to the rank of a principal arm. Its decisive effects, at the late battles on the Rio-Grande, are supported by testimony too emphatic to be overlooked.

Worth noting, in this passage, Mahan left a footnote, not to Captain Samuel Ringgold as one might guess, but rather to Joel R. Poinsett. He gave the former, and late, Secretary of War credit for reforming the US Army and ensuring the the force was ready for the test of combat… and we have discussed his artillery reforms on occasion.

Mahan continued on, lauding the artillerists of his day:

From the studies required of him, the artillerist is well trained to maintained the characteristics of his arm; courage of the highest order, in which the physical is always under the control of the moral element, producing, as necessary result, unbounded devotion to the task assigned; a presence of mind that nothing can disturb; and that coolness which no danger, however appalling, can impair.

Ladies and gentlemen! I give you Marvel’s new super hero! Artilleryman! If nothing else, a description that we should all aspire to.

Turning back to serious matters, we have that question about “place” … not in the metaphorical sense… but as in WHERE to put the cannons. And Mahan got around to that:

The tactical applications of artillery on the field depend on the caliber. To the heavy are assigned the duties of occupying positions for strengthening the weak points of the field of battle; for securing the retreat of the army; for defending all objects whose possession might be of importance to the enemy, as villages, defiles, &c.; and for overturning all passive obstacles that cover the enemy, or arrest the progress of the other arms.

Although the distinction of “heavy” artillery would drop just over a decade after Mahan wrote this passage, the guidance remained valid. More to the point, we see examples of how the artillery might be placed to, as I put it, take away options from the enemy. In particular turning weak points into strong ones, retaining possession of key terrain, and countering passive obstacles.

As for the light artillery:

The light pieces, served by foot-artillery, follow the movements of the infantry; covering the flanks of its position, preparing the way for its onset, and arresting that of the enemy. It is of this that the principal part of the artillery in reserve is composed.

Employed directly to support the infantry, artillery prevented the enemy from arresting (not stopping… words have meaning) the friendly advance. Likewise on defense, the artillery arrested the enemy advance. In both cases, that translates to taking away options open to the enemy commander. Perhaps others will expand that role to MAKING options for the friendly commander… which would also be a good way to put it.

The horse-artillery is held in hand for decisive moments. When launched forth, its arrival and execution should be unexpected and instantaneous. Ready to repair all disasters and partial reverses, it, at one moment, temporarily replaces a battery of foot, and at the next is on another point of the field, to force back an enemy’s column. In preparing the attacks of cavalry, this arm is often indispensable and always invaluable; brought with rapidity in front of a line, or opposite to squares of infantry, within the range of canister, its well-directed fire, in a few discharges, opens a gap, or so shakes the entire mass, that the cavalier finds but a feeble obstacle, where, without this aid, he would in vain have exhausted all his powers.

Three “places” for horse artillery offered as examples: rushed to replace a pressed battery of foot; dispatched to break an enemy assault; or used to prepare the situation for a cavalry charge. In that latter role, the artillery moved forward within canister range… that’s C-A-N-I-S-T-E-R… not grape-shot. And that is considered between 200 and 400 yards. Musket range, before the wide adoption of rifles and mine-balls, was still considered at 100 yards. Arguably, even after technology allowed for more range, the infantry tactics still governed engagements with the musket at 100 yards.

Note that not once does Mahan suggest the artillery should, themselves, charge forward. None of these alleged artillery charges. It simply was not part of the doctrine which he described here. Artillery was not supposed to BE the attacker. Artillery was supposed to make the way easier for the attacker.

Another take-away from this passage is the alignment of the horse artillery. As Henry Hunt would argue during the war, the horse artillery was not simply assigned to support the cavalry. Rather the horse artillery should be a general reserve, used where the situation warrants. If that be supporting the cavalry in its mission, then so be it. But the horse artillery also had a role outside of that. And often that was far more important than simply aiding the defense of distant picket posts.

If nothing else, these passages, across but three pages in the manual, refute many preconceptions about how artillery was to be employed. The guns were not to be wasted simply standing in an augmentation of the infantry line, belching canister. Such would simply be employing the guns with their casualty-creation ability in mind. Instead the artillery was there to influence the battlefield situation, with focus on the cannon’s ability to exert control over a greater distance than capable with the other arms. In such way, we see the value of the artillery – its value as a combat force multiplier – in exponential terms.


(Citations from Dennis Hart Mahan, An Elementary Treatise on Advanced-guard, Out-post, and Detachment Service of Troops, and the Manner of Posting and Handling Them in Presence of an Enemy, New York: John Wiley, 1861, pages 45-7.)

Artillery on the Battlefield: Tactics according to Mahan

Looking back at last year, one highlight of, as the disciples of social media say, the “content offering” from this blog was the Artillery tour of First Manassas, held jointly with Harry Smeltzer of Bull Runnings fame. The objective was to analyze the artillery employment at First Manassas with an eye to what we call, in the modern terminology, the tactical doctrine. Not to say things like “I could have done it better” or even “this is where he/they screwed up.” But rather specifically to ask if the employment was “by doctrine” – as in what a commander was expected to do – or was there some innovation going on, either intentional or unintentional. The preface to that “on the field” discussion was a series of quotes from pre-war writings, mostly in manuals that the officers of the time would be exposed, about the use of artillery on the battlefield.

First off, when discussing Civil War tactics, we have to pause and recognize things called “tactics” then were not necessarily what we call tactics today. As such our discussion has to incorporate some translation. For instance, a book titled “Field Artillery Tactics” from 1861 tends to be more so a manual detailing drill of artillery (from the artilleryman up to the battery level). That sort of thing is important, as the complex choreography involved with moving and servicing a gun must be part of the context. But when addressing the question posed above, in relation to the placement and employment of the artillery, we are left wanting descriptions about how a commander should use the artillerymen and their wonderful cannon.

For modern times… pretty much anything since the dawn of the 20th century, I could point you to a series of Army manuals that take us through the entire spectrum – technical manuals, drill manuals, and tactics manuals, all labeled as such. More to the point, I could reference manuals for tactics at the squad, platoon, company, battalion, regiment/brigade, and division level… or for artillery, by gun, section, battery, and battalion. But for the Civil War, we lack such granular detail. I don’t take that so much as a knock on the discipline of military science as practiced at that time, but more so a shortcoming due to a lot of presumptions. The foremost of those presumptions was that a young officer would receive all the tactical training needed at his first duty station. More so, an officer would be “indoctrinated” to the nuances of handling a cannon, a section, or a battery under fire; and further along become aware of the manner in which those guns should be employed. That’s a peacetime luxury, of course. Rapidly expanding armies and the pace of the war outstripped such an indoctrination system.

Still, there should be, and was, a starting point for those discussions. And I submit if we are going to point to one manual that was the American starting point, that was Dennis Hart Mahan’s An Elementary Treatise on Advanced-Guard, Out-Post and Detached Service of Troops, and the Manner of Posting and Handling Them in Presence of an Enemy, with a Historical Sketch of the Rise and Progress of Tactics, &c., &c., Intended as a supplement to the System of Tactics Adopted for the Military Service of the United States, and Especially for the Use of the Officers of Militia and Volunteers. (Yes, I like to introduce that title when playing charades.) Or as many simply refer to – Mahan’s Outpost.

Right off the bat, we see from the full title that Mahan intended his manual to further the discussion based on the established system of drill, called tactics. And considering the original publication date, in 1847, this “system” was that defined by General Winfield Scott. Those were, arguably, tested by fire and deemed sound. But those focused, as alluded to above, on how to move infantry, cavalry, and artillery. Not much in that system as to the “why” one would want to select a particular movement over another… in other words, what we today perceive as tactics. The problem was that officers in the lower echelons were often never exposed to the theories and practices beyond drill. And in the American experience, where grand armies had rarely taken to the field, it was those same junior officers often entrusted with vital operations.

Mahan hit upon that gap in the preface to his treatise:

The suggestion of this little compilation originated in a professional intercourse, some months back, with a few intelligent officers of the Volunteer Corps of the city of New York.

The want of a work of this kind has long been felt among our officers of Militia generally, as the English military literature is quite barren in systematic works on most branches of the military art, especially so on the one known among the military writers of the Continent as La Petite Guerre, or the manner of conducting the operations of small independent bodies of troops….

Wouldn’t you have wanted to be a fly on the wall during that discussion in New York?

Mahan opened his manual with a chapter covering the historical evolution of military science. Then started chapter two with the definition of “tactics”:

Tactics may be defined to be the art of drawing up, and moving troops systematically. It admits of a classification into two divisions. 1. Minor or elementary tactics; under which head may be placed all that refers to the drill, and other preparatory instruction of troops, to give them expertness in the use of their weapons, and facility of movement. 2. Grand tactics; or the art of combining, disposing, and handling troops on the field of battle.

This explains, somewhat, that translation I mentioned above. What we’d call “drill” today, Mahan considered minor or elementary tactics. And it is those “grand tactics” which we want to consider here. Most specifically, how did the artillery factor into those grand tactics. What, according to Mahan, was the artillery supposed to do on the battlefield? Well we turn to page 39:

The artillery is placed third in rank among the arms. Its duties are to support and cover the other arms; keep the enemy from approaching too near; hold him in check when he advances; and prevent him from debouching at particular points.

There, in one lengthy sentence, is the role of artillery on the Mahanian battlefield. Mahan’s vision of this is not just some passage in a book. This was part of the curriculum taught to his students, and his student’s students. Indeed, the majority of Civil War generals had benefit of Mahan’s teaching, either directly or indirectly. So this is an important passage when considering how artillery was used or mis-used on a Civil War battlefield.

Looking at this deeper, consider the nuances here. In the Mahanian context, the infantry and cavalry have the first and second rank, respectively. Their roles are tied to objectives, be that a piece of territory or imposition of a situation. But we mostly think of them as seizing and holding terrain. We might add to that the cavalry’s capacity for gathering information (actively or passively, as in scouting or picketing, respectively). But in the grand sense, the infantry could do the same, but as in all things just slower than the cavalry.

But artillery’s role was not tied to those higher order objectives. Rather to support the infantry and cavalry in attaining those objectives. But how is that done? By effecting enemy actions and activities – keep that enemy at a distance; stop or at least weaken an enemy attack; and deny the enemy use of good terrain. I like to put it this way – and this is my translation of Mahan for our modern ears: The role of artillery is to deny the enemy commander a course of action.

Deny a course of action? Yes. Roll that around for a bit. Try this exercise for any artillery position you’ve considered on a Civil War battlefield – From that point, what influence did they have on the battle? In every case, that will devolve down to the artillery either preventing or not preventing an enemy from executing a course of action. Maybe that course of action was to move up a particular route to attack. Maybe that course of action was to form a defensive line. Or maybe the artillery simply prevented, just by being there, the enemy from selecting a road other path for use in battlefield movement. But either way, the success of the artillery at that position was measured in the impact it had on the enemy commanders’ actions, specifically the courses of action available. Or if you prefer, the enemy commander’s options.

I would submit that if that be a positive influence (for the “home” side of that artillery) then the guns were well placed, and Mahan would have been happy. Were that be a negative influence on the battle, particularly where the guns became the “objective” instead of being the support for the other arms, then Mahan would have contended his lessons went unheeded.

Fortification Friday: Mahan’s American Blockhouse

One of the themes I’ve worked in this series of posts is a comparison between pre-war and post-war manuals. In small ways, the comparison points to the influence of wartime experience in the practice of military science… at least in the American army.  Another such example is the use of blockhouses.  Pre-war, Mahan discussed blockhouses in relation to field fortifications as a safety redoubt or keep.  That was not, of course, to say such was the exclusive use of blockhouses.  But Mahan simply offered less thought about the use of stand-alone blockhouses. Rather the emphasis was upon structures which would be used in conjunction with standard, conventional field fortifications to meet the traditional needs of an army on campaign. Again, this is not to say Mahan didn’t agree with stand alone blockhouses, but rather that in instructions to his students he put all the emphasis on blockhouses used as keeps within field fortifications.  So this is a “how they were taught” consideration instead of a “this is the only way they would use it” declaration. Keep that fine point in mind.

On the other hand, the American military experience, drawn out even more so by the Civil War, included the need for fortifications guarding rear areas.  In particular, protection of railroad lines, bridges, and other such infrastructure was rather important. And, as we know from ample examples from official records, photographs, and other sources, the blockhouse became the preferred fortification for that need.  And Mahan identified that in his post-war writings, declaring an American-ism in such employment:

American Block-House. In the more recent block-houses erected in our service for the protection of bridges, railroad stations, etc, the sides and roof … are constructed with a double thickness of logs eighteen inches in diameter, hewn to a face of eight inches where they are in contact.  The inner logs are placed upright, the outward horizontal. A space is left in the outward casing sufficient for the fire from the loop-holes made through the inner. The horizontal logs above the loop-holes are held up by short uprights, mortised into them and into those just below. The ceiling is covered with earth, as shown in the section, three feet thick at the ridge and sloping towards the eaves to about six or nine inches, where it is confined by a pole plate. The earth is protected from the weather by a board roofing.  Tin or sheet iron ventilators are made through the roofing and ceiling, and a brick flue to receive the pipe of the stove used in cold weather.

The loop-holes are nearly of the same form and dimensions of those already given.

Mahan gave us two sets of illustrations supporting this passage.  The first demonstrated the blockhouse particulars mentioned above:

MahanFig48_49_50

We see a double layer of timbers – the inner most placed vertical and the outer laid horizontally. In both cases, the logs are flattened on the sides in contact to close up any gaps.

Also notice the provisions for loopholes.  The dimensions remained the same, generally. But instead of simply carving out loopholes, Mahan suggested a more elaborate arrangement.  I’d describe this as a set of small columns between a gap in the outer, horizontal timbers.  Traditional loophole cuts are made in the vertical timbers of the interior. So there is still the double row of protection and the minimum opening required for the musket barrel.

I say a picture is worth a thousand words:

02147r

This is a blockhouse protecting the railroad between Nashville and Chattanooga in Tennessee.

Continuing, Mahan offered more elaborate plans for these blockhouses:

Some of these structures are built in the form of a cross, consisting of a square central chamber, twenty-four feet on a side, and of four wings of the same form and dimensions when the block-house is for cannon. An embrasure is pierced in each of the three sides of each wing to serve a single gun.  The cheeks of the embrasures are faced with logs, and the mouth is secured by a musket-proof shutter with a loop-hole in it.  The embrasures are below the level of the loop-hole, allowing these to be used whenever necessary.

Though not exclusively for the employment of artillery, the implication is that guns required more space within the fort and thus more elaborate arrangements were needed.  The addition of shutters is noteworthy and speaks to the need for crew protection in the era of muzzle-loading artillery.

But where you have artillery, you must also have a magazine:

Arrangements for magazines and store-rooms are made under the floor of the block-house in the most secure parts.

Ah… OK… answers that question.

And what about the entrance:

The entrance to the block-house may be either through a postern, the bottom of which is on the level of that of the ditch, a ramp leading from this level outwards, a door properly secured, and steps, forming the inner communications; or it may be arranged as shown in Fig. 51, 52, with a plank thrown across the ditch on the same level as the natural ground, the entrance to the door being masked by a double stoccade, leaving the same passage-way as that of the doorway.  Loop-holes in the door and sides of the building sweep this passage.

And here’s the referenced figures:

MahanFig51_52

Also note in this set of figures, and that above, the berm built up against the blockhouse.  As discussed earlier, this improved the defensive quality of the work, particularly against artillery.  Furthermore it prevented the enemy from hiding under the loopholes.  We don’t see that in the wartime photo above.  I’m of a mind we are seeing a blockhouse in the final stages of construction, rather than some flaw in the engineer’s design.  Other wartime photos show earth banked up against the blockhouse:

02151r

This is another Tennessee blockhouse.  Wonderful details to consider – the loopholes and the entrance stand out nicely.  And consider the figure offered by Mahan (post-war) to illustrate the two story blockhouse:

MahanPage65Fig1_2

Can you find a better match? That’s great stuff!

Another illustration Mahan provided in the post-war manual detailed arrangements for the loopholes.  So while he “said” such was “already given,” teaching after the war he saw need to elaborate.  We’ll look at that next.

(Citation from Mahan, An Elementary Course of Military Engineering: Part 1: Field Fortifications, Military Mining, and Siege Operations, New York: John Wiley & Son, 1870, page 62-3.)

Fortification Friday: Loopholes and Vents for the blockhouse

Last week, we discussed the layout and arrangements for the blockhouse, when used as part of a keep in the interior of a fortification.  An important requirement, if the keep was to function as intended, was the ability of the defenders to fire out of the blockhouse.  Just as with building the banquette, embrasures, and other arrangements on the parapet, such arrangements within the blockhouse necessitated attention to details. And those details come in the form of loopholes and vents, as Mahan would write:

The loop-holes are three feet apart; their interior dimensions are twelve inches in height; and eight inches in width for sides twelve inches thick; and twelve inches square for sides two feet thick. The width on the exterior, for the same thicknesses, will be two-and-a-half and four inches.  The height of the loop-hole on the exterior will depend on the points being defended; it should admit of the musket being fired under an elevation and depression. The height of the loop-hole above the exterior ground is six feet.

The visual you should have in mind is that of an aperture which is small on the exterior but larger for the interior.  This would allow the defender to train the musket across a wide arc, as well as providing for elevation and declination.  I don’t like mixing field fortifications with permanent fortifications, but in this case the application is along the same lines.  So consider the loop-holes here at Fort Pulaski, to the right of an embrasure:

Ft Pulaski 3 Aug 11 1346

In this case, there was need for the muskets to cover two zones.  So we see two loopholes incorporated as a pair.  Note the placement of stone slab above and below to strengthen the loophole structurally. Something not needed within the wooden blockhouse – simple cut outs within the timbers usually sufficed.

But the major difference between the blockhouse and brick fortification’s loopholes is the height.  Mahan specified only twelve inches for the blockhouse in a field fortification.  Those at Fort Pulaski are two feet or so.

Another aspect to keep in mind is the depth of the wall.  As the wall became thicker, the loophole’s lateral dimensions, particularly interior, increased.  Geometry at play here, as the musket would need more clearance on the interior as depth increased.

Mahan did not directly discuss interior arrangements for the artillery’s embrasures.  Partly, I think, as such an allocation would have pulled valuable cannons off the fort’s primary defensive line to that of the secondary or even tertiary defenses. But, we can deduce such arrangements would match those described for embrasures through the parapet.  In short, a larger loophole… which is what we see to the left of the photo above.

All this is good thinking.  But we also have to keep in mind the by-product of firing any weapon.  In order to push the projectile out of the barrel, firing of the powder creates gasses. That foul air is not an issue out in the open or on the parapet.  But in the enclosed space of the blockhouse, there is need to expel the gasses:

Vents for the escape of the smoke are made over each loop-hole, between the cap-sill and the top pieces.

Moving to another location in Fort Pulaski, we see a vent above one of the other embrasures:

Ft Pulaski 3 Aug 11 1388

See the weathering on the paint?

Mahan does not provide much information on constructing vents for the blockhouse. These could be vents between the ceiling and wall. Or vents incorporated in the wall itself.  To maintain integrity of the structure, in terms of defense, those vents were best created using an interior angle.  That would allow gasses to vent.  But water… or things the enemy might want to push inside… would be restricted.

From there, Mahan gave brief descriptions of the camp bed (which we noted served as the banquette inside the blockhouse), racks, and other storage arrangements.  But with that he left the interior arrangements.  Instead he turned to an external details.  We’ll look at those next week.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, page 64.)

Fortification Friday: “a redan or a lunette, is thrown up on the exterior to cover the outlet”

Before we close the discussion of openings for forts (see what I did there?), let me circle back to compare Mahan and Wheeler in regard to one of the fine points considered.  That being the use of a detached redan or lunette in advance of the outlet.  Recall that in pre-war writing, Mahan suggested:

In very frequented passages, a redan or a lunette, is thrown up on the exterior to cover the outlet, and thus ensure its safety in case of surprise.

And Wheeler, in the post-war, mentioned a similar arrangement, but perhaps narrowed the application to those larger outlets, for sorties, where simple interior traverses would not be practical.

Mahan offered two figures that illustrated the redan to the front of an outlet:

PlateVIIFig48_49

Figure 48 offers a wide redan in front of an outlet, which is further covered and flanked by by the “horns” of the larger work.  A very well protected outlet, we might say.  Mahan considered this a Redan Line.

On Figure 49, we see much more complexity.  Particularly with the defensive lines of fire.  The outlet is nested within a redan of a larger line.  On both sides are faces within redans of differing angles. This is considered a Tenaille Line – a proper definition we will discuss later.  But the point being the covering redan, to the front of the outlet, was absolutely necessary here in order to protect that weak spot.  The covering redan is somewhat off center of the outlet, perhaps to limit exposure at the expense of accessibility.

Wheeler, as you may recall, gave us only a simple rendition of the covering redan:

WheelerFig51

The question I have in regard to these advanced, detached “parts” covering openings is… just how often were these employed during the Civil War?

When examining surviving earthworks, we often find the area around the outlets obliterated.  Sometimes, due to necessity, that is done to facilitate visitor access.  But more often, just a case where the structures around the outlets were the most susceptible to erosion.

And when examining wartime plans, we see some use of these redans… but more often not.  Consider Fortress Rosecrans outside Murfreesboro:

FortressRosecrans

This was, some have said, the largest fort built during the war.  And in this plan we see examples of many features suggested by Mahan.  Specific to the outlets, we see up near the top that Battery Cruft was a detached lunette (maybe a “half lunette”) covering an outlet.  Elsewhere, such as next to Lunette McCook at the bottom right, we see an outlet (an existing road) without a covering redan or traverse.  Though we do see obstacles erected to the right of Lunette McCook.  And certainly that named work was positioned to dominate the approaches to the outlet.  Furthermore, what you don’t see in my “snip” are works in advance of the fortress that covered the railroad and road.  Though those were oriented south and not regarded as covering the outlet in question.

Another plan to consider is from Virginia, at Deep Bottom:

DeepBottomSnip

Here we see five road crossings at the main line of the works.  One of those is blocked entirely by a redan.  The other four (including one that appears to be a path cut just to clear a redan) have no traverses or covering works.  Just obstacles placed in front.

If we are assessing the protection of outlets, with Mahan’s suggestions in mind, we find a mixed application of those covering redans.  Seems to me the use of that sort of feature was based on the engineering assessment of need.

Now considering such use under Wheeler’s suggested implementation, let’s look to the location of a few large scale sorties.  First, how about the works were the Crater assault was mounted:

CraterSector

And further around the lines, and further forward in the historical timeline, to the sector around Fort Mahone:

FortMahoneSector

And to the left of that sector near where the Federal Sixth Corps mounted their sortie:

FortWelchSector

Now the scale of these maps mean these are not so much “plans” as operational maps.  So we know there are structures that escaped the pen here.  But what stands out, with double underlines, is the use of something far more elaborate than Mahan and Wheeler discussed.  We see entire sections of works advanced in a manner to provide staging grounds for those formations preparing for the assaults. Major assaults, mind you, involving whole divisions.  These were, you see, works built for the offensive.  Grand offensives!  In that light, might we say the entire Federal line was one large “covering work” in front of an array of staging areas and supply depots?