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.)

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

  1. Craig: Its instructive to remember that while the Union embraced batteries with single types of guns, the Confederates did not. This proved to be an ordinance headache.

    • Indeed…. and the same can be said of the Federal batteries in the less-well-supplied theaters. In both cases, the issue was more so making due with what was on hand, as opposed to some tactical preference. I would point out that the Confederates would often “task organize” within the batteries, detaching sections of howitzers and grouping such, in order to get around their mixed battery problems.

    • Peter: Of course, into 1862 there were still some federal batteries in Virginia that had to deal with the variations in range and ammunition when calibers were mixed. One incident that has always struck me involved Wiedrich’s 1st NY Light Battery I at Second Bull Run, Day 2. When Wiedrich was summoned to Chinn Ridge to respond to Longstreet’s attack, he took only his four ordnance rifles and left his two 12 lb. howitzers behind because of range limitations. As Craig indicates, this was more of an ongoing issue for Union artillery in the “western” theater.

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