Relative Combat Effectiveness
of Napoleonic Artillery
by Howie Muir, Burkina Faso
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Q: What is the difference between a 4 pdr and 12 pdr round shot upon arrival at its target? Well, O.K: to put the question another way, what is the practical, functional difference between the fire effectiveness of a four pounder and a twelve pounder battery in the field? Are there others – wargamers, re-enactors, or historians – who have light to shed on this query? The literature that I've encountered related to the subject of artillery's relative "destructive power" is at the same time both disarmingly clear and contradictorily fuzzy, although it may only be a matter of emphasis. While laying no claim to exhaustive research, unadorned physics suggests to me that a cannon ball in flight was lethal to anyone standing in its way. Full stop. To put it simply, the principal difference between various calibres of ordnance pieces would appear to me to have been the distance at which they could project their fire – i.e. keep the cannon ball in flight and therefore lethal. In fact, the same would apply to canister, more or less. While the histories are replete with accounts of the "spent" musket ball miraculously failing to do much more than bruise its target, I have yet to encounter a story of anyone less than seriously maimed who met a "spent" cannonball still in motion. With respect to the "damage" that a 12pdr versus a 4pdr ball would do, the actual dimensions of the shot would also seem irrelevant to the question: their diameters were separated by a mere one inch and a half [1] – the heavier ball did not hit any more targets in a formation through which it passed than its lighter cousin. Nor does it seem imaginable that a human body was sufficiently dense to deflect either calibre of ball from its trajectory.
As Brent Nosworthy phrased it in Battle Tactics of Napoleon and His Enemies [2], "Most of the projectile's kinetic energy was superfluous for the task at hand: the destruction of horseflesh and human matter."
"Human flesh and blood had little impact on the course of a 4 to 12 pound iron spheroid travelling at little more than 2,000 feet per second [3]. A cannon ball possessed sufficient kinetic energy to pass through dozens of men, if they were all unfortunate enough to find themselves along the same path of destruction." [4]
Firepower
The British artillerist, Maj.-Gen. BP Hughes put it this way in his work, Firepower: Weapons Effectiveness on the Battlefield, 1630-1850:
"Round shot had two purposes: to breach walls of fortresses in siege operations, and quite simply to destroy men, horses and equipment in the field. In the latter role, even when of small size, it was devastating to those who stood in its path and within its range. It could shatter a gun carriage or wagon and slice men or horses in half, doing either in a noisy and frightening manner. There are records of as many as forty men having been killed by a single shot at a range of 600 to 800 yards, all having been in the line of fire at the time." [5]
The penetrative power of a round shot, of whatever calibre, against living matter was truly awful – in the above example, lethal across two hundred yards. The difference in "hitting power" only mattered, however, when endeavouring to penetrate works or to breach a fortress wall.
Nevertheless, wargame rules – where there is usually an attempt to quantify such things – invariably allot to heavier guns a greater capacity to inflict casualties at any given range. And, indeed, military historians write passages that would frequently appear to suggest exactly that deduction. Yet, on closer reading, the same historian will often have written something curiously to the contrary elsewhere in the same work. BP Hughes, earlier in the work quoted above, opined that, "In general, the bigger the calibre of a piece and the heavier its projectile the longer its maximum effective range and the more destructive its fire [italics added]." [6]
In the course of explaining in an earlier work, Open Fire: Artillery Tactics from Marlborough to Wellington, why the commander of Wellington's horse artillery at Waterloo re-armed almost half those batteries with 9pdrs, Hughes mentions:
"The remaining velocity, that is the speed of the projectile at the end of its trajectory, increased appreciably with the calibre. The kinetic energy of the round shot, which depended upon the square of the velocity as well as the weight of the projectile, was therefore markedly higher in the larger calibres. So the destructive power of the 9pdr was three times as great as that of the 6pdr...[italics added]" [7]
And again, in his later Firepower, Hughes reiterates:
"It is important to appreciate the effect of the weight of the shot. There was little difference between the muzzle velocities of all the guns used in the field, but the heavier the shot the greater was its remaining velocity – that is, its velocity at the target. The destructive power [italics mine] of a shot depended upon its kinetic energy, which varies directly with the weight but according to the square of the velocity. The heavy shot was therefore possessed of appreciably more hitting power than the light shot. Again, according to Müller, in relation to a 3pdr shot a 6pdr shot was fifty percent more effective and a 12pdr shot was twice as effective. It is a point worth bearing in mind when studying the battles." [8] [this math is at variance with Müller's math to his own assessment in Open Fire, above.] Similarly there lurk intimations of the increased destructive power of heavier calibre guns in Nosworthy as well: "Damage was caused by the impact of the projectile against the target, and was proportional to the weight of the projectile and its velocity at impact.. The heavier the round shot, the greater striking power at long distance." [9]
Philip Haythornthwaite, in a concise explanation of Napoleonic artillery performance, echoing the same primary source as Hughes in Firepower above, also gives an implication of heavier guns' greater destructiveness :
"Though muzzle-loading velocities of cannon were similar, the increasing weight of shot greatly increased the effectiveness of the round; thus the artillerist Müller calculated that a 6lb shot was 50 percent more effective than a 3lb, and a 12lb twice as effective." [10]
Effectiveness vs. Destruction
But what is meant by "effectiveness" and "destruction"? The wargame designer, for example, desiring to quantify performance, could under-standably find in this description grounds for awarding to heavier guns greater power to inflict casualties at a given range.
It appears that most writers have adopted terms like "effectiveness" and "destruction" to describe the overall correlation of artillery's performance, factoring frequency of fire, type and quality of ammunition (weight of shot, volume of canister, technical advantage of shrapnel), and range at which fire could be projected with reasonable effect. While simple enough, and perhaps self-evident, these generalisations seem to have a surreptitious effect on the specifics of subsequent perceptions and deductions that can produce some paradoxical results. Hughes cites in Open Fire, a spectacular example of the greater "destructiveness" of heavier guns, "an incident which took place in 1854 at Inkerman":
"There two 18pdr guns of the siege train were brought up to reduce the effect which was being produced on the Allied infantry by no less than 100 Russian field guns in action on a ridge overlooking the battlefield. Coming into action at a range of just over 1000 yards, those two heavy guns incredibly either destroyed or drove from the field the whole of those hundred guns. It was pointed out earlier that the destructive power of the heavier projectiles of smooth- bore artillery equipments exceeded that of the lighter equipments by a surprisingly large margin." [11]
(Some fifty pages earlier, Hughes reckoned that, "The destructive effect of the 18pdr was no less than ten times as great as the 6 pounder." [12]) He also refers to the incident in Firepower:
"The heavy shot of the British guns overpowered and destroyed in succession the guns of a large battery of Russian field artillery, whose return fire was largely ineffective." [13]
Yet, in what way did gun calibre improve destructiveness? Hughes stated earlier in Firepower (quoted above), in apparent contradiction, that if a round shot, whatever its weight, struck a gun carriage, it was likely to do critical damage. Most authors, Hughes included, agree that in counter-battery fire, the tricky thing was the accuracy needed actually to hit the hostile guns; counter-battery fire was widely regarded as an inefficient expenditure of ammunition to be avoided, but ". . . though many rounds may have to have been fired to obtain a hit [against an enemy battery], a single hit by round shot on the wooden carriage of a gun would almost certainly disable it or dismount the piece." [14]
"Destructiveness" does not count for much beyond the destruction of the target. In fact, not specifically mentioned by Hughes in this instance, it was not so much that the shot was heavier nor the calibre bigger that made the British guns more "destructive", but rather the capacity that the weight of an 18 pound shot coupled with the larger guns' capacity to bear a bigger charge of propellant that enabled them to out-range their opponents that was critical.
To be specific, this meant that at 1,000 yards the British 18pdrs were more accurate than the lighter Russian guns. A fact well known to Hughes that, for whatever reason, he neglected to explicate, leaving a potentially fuzzy conclusion to be drawn by the reader.
Power vs. Range
Curiously, in his above reference in Firepower to the importance of the velocity of the cannon ball when arriving at its target, Hughes left as a footnote information drawn from the primary source of the Madras Records that makes dramatically clear how different was the power and range of heavier calibres versus lighter guns when measured by the shot's velocity upon reaching a potential target at 1,000 yards, the far edge of typical engagement ranges: 18pdr - 840 fps [feet per second]; 9pdr - 690 fps; 6pdr - 450 fps. [15] In most engagements, however, range (a function of velocity) was arguably the more important aspect of speed than the force with which the ball struck its target.
Also noteworthy, is that on this same page – the principal page devoted to the general and comparative discussion of the performance of artillery round shot, and which refers both to the events at Inkerman (discussed above) and the up-grading of Britain's 6pdrs to 9pdrs in the Peninsula as well as among the horse artillery at Waterloo (discussed below) – the comparison of ranges is never raised! While general ranges are explored, the only other comparative remarks again emphasise "hitting power" by reference to the "important" inability of a gun lighter than a 9pdr to penetrate enemies' earthworks – as though earthworks figured significantly in more than a fraction of Napoleonic battles. [16] Issues of comparative range advantage are left by the wayside.
Indeed, it is the concern about being out-ranged that seems to concern contemporaries rather than simply some sense of the intrinsic destructiveness bequeathed by the weight of the shot. Range and calibre (and thus shot weight) are, of course, two sides of the coin, and therein lies a source of intellectual fuzziness. As Hughes explains, "In general, the bigger the calibre of a piece and the heavier it's projectile the longer it's maximum effective range and the more destructive its fire" [17] – oh, no: there's that "destructive fire" concept again! Notwithstanding the non-specificity of "destruc-tiveness" here, presumably to be equated with the power of the shot at impact ("hitting power"), Hughes is indisputably correct to say that range is a factor of calibre and projectile weight as well as charge and barrel length, as he describes a page before:
"A gun was designed to impart the highest practicable muzzle velocity to its projectiles, not only to give them the greatest possible range [italics added] but also to increase their hitting power. This demanded a long piece, so that the gases produced by the exploding propellant charge could act upon the projectile for as long a period as possible. At the same time, with the ratio of charge weight to projectile weight as high as it could be, the calibre – or size of the bore – was limited by the ability of the metal of which the piece was made to withstand the stresses placed upon it. The gun therefore had to be long and thin, its length between fourteen and twenty-four times its calibre." [18]
Nosworthy, cites Hughes's explanation [19], and goes on to illustrate the importance of different designs with an interesting national comparison between French and Austrian barrel lengths.
". . . in an attempt to gain greater mobility, the Austrian guns were endowed with slightly shorter barrel lengths than their French equivalents. In Austrian service, the length of the barrel was sixteen times the calibre of the bore, rather than the eighteen found among French ordnance. The Austrian gunners, as a consequence, were required to use slightly less explosive powder for each charge – about the quarter of the weight of a bullet, instead of a the one-third rule followed by the French artillerists.
"Writing after the conclusion of the Napoleonic Wars, a French ordnance officer pointed out that this difference in the propulsion charge was anything but trivial. A series of trials comparing the accuracy of differing calibres of ordnance with varying charges, demonstrated that the larger pieces using optimal-sized charges (equivalent to about one-third of the weight of the projectile) were more accurate at longer ranges [italics added]. Many artillery officers, both British and French, felt the French artillery also possessed a similar advantage over their British counterparts." [20]
Indeed, as will be seen below, it was the concern for being out-ranged that led the British to replace their 6pdrs with 9pdrs.
Juicy Generalization
Yet, even Nosworthy could not resist the temptation of a juicy generalisation of overall comparative advantage. Consider the omitted text following my added italics above:
"This French officer's analysis provides the scientific basis for Scharnhorst's empirical observation, made during the height of these wars, that two French 8pdrs were as effective as three Austrian pieces of the same calibre, two French 12pdrs were equivalent to three Austrian 12pdrs or five 6pdrs [from Caraman (Marquis de), 'Du service de l'artillerie en campagne', Spectateur militaire; Paris, vol. 6, 1830; p.417]." [21]
Very illustrative, and provides the sort of quantifiable, competent observation that a wargamer or an historian would crave. Even within its broader context, however, the precise meaning of "effective" remains vague: to suggest that overall, general effectiveness across all ranges and with all ammunitions is not the same as the possible conclusion that at any given range the different gun calibres possessed the above equivalencies.
Curiously enough, some of those perceived differences in capabilities might be attributed as well to the differences by which nations gauged their measurements. According to Haythornthwaite's research, "an Austrian 12pdr calculated on the 'Vienna pound' (0.83 of a British pound) had a very much lighter shot than a French 12pdr calculated on the 'Paris pound' (1.08 of a British pound), the respective weights expressed in British measure being 9.96lb : 12.96lb, hence the superiority of ordnance using a heavier pound against guns of the same 'nature' [calibre] but calculated on a lighter 'pound'." [22] Thus, a French 12pdr, throwing a shot some 30% heavier than its Austrian counterpart and with a roughly 33% more powerful charge down a 12.5% longer tube, would have boasted a somewhat greater effective range.
After exploring the perspectives offered by Hughes, Nosworthy, and Haythornthwaite, George Nafziger's Imperial Bayonets: Tactics of the Napoleonic Battery, Battalion and Brigade as Found in Contemporary Regulations provides a refreshing resource for primary research and statistics which occasionally confound modern, received wisdom. With respect to the effectiveness of round shot, whether employed in direct fire or in ricochet, my attention was drawn to two tables, "Accuracy of high angle fire with round shot" and "Accuracy of skip or roll shooting. The first table, drawing on five sources of experimental research by contemporary artillerists, compares 6 and 12pdrs' accuracy against a company-wide target under what are likely to have been "optimal" conditions (no battlefield smoke to obscure the target, no mind-numbing din, no distracting threat to life and limb, no horrifying carnage, no awkward terrain, no pressure to fire faster, no losses among the crew or interruption to ammunition flow). As Nafziger points out, for direct, "high angle fire" the 12pdr was unsurprisingly more accurate at long range than the 6pdr. At least as interesting, however, is how little the percentages of hits by guns of each calibre diverge until after 900 meters – about 1000 yards, or the widely regarded far edge of battlefield engagement range. Even more surprising is that their average accuracy appear to converge as range approached 900 meters, before significantly diverging! At 600 meters, the 6pdr was 80% as accurate as the 12pdr (46.2% of shots struck their mark versus 55% of shots), at 750 meters, 87.5% as accurate (39.5% : 45.1%), at 900 meters, 88.5% as accurate (31.2% : 35.2%), and then 63% as accurate at 1,200 meters (15.8% : 25%)." [23]
The experimental research of three of the same contemporary artillerists, again under presumably optimal conditions, provided the basis for an assessment of ricochet fire, a method by which both the range and the shot's lethal zone were considerably extended. Although accuracy with this method suffered, Nafziger remarks that, "It is interesting to note that the accuracy for this type of fire does not seem to vary with range. It appears that any skip shot had approximately a 25% chance of striking its final target." [24] Not only did accuracy appear not to diminish with range, but it there was no meaningful difference of accuracy between the 6pdr and 12pdr gun when using ricochet fire(!): on average, at 980 meters (again, already at the edge of traditional engagement range), the 6pdr was 96% as accurate as the 12pdr (24% : 25%), at 1,130 meters, 90,7% as accurate (22.5% : 24.8%), at 1,200 meters, 102% as effective (21.5% : 21%!), and then 103% as accurate at 1,350 meters (24% : 23.3%!!). [25]
Nosworthy's research appears to corroborate Nafziger's. Citing Scharnhorst's "experiment to ascertain the effectiveness of ricochet fire and direct fire" (as drawn from Caraman, 'Service d l'artillerie', p.416), Nosworthy describes 30 minute trials with 6 and 12pdrs conducted against a target 200 feet wide by six feet high. Note that, "It was observed that the 12 pounders fired approximately three rounds every two minutes, while the 6 pounders fired on the average four rounds during that same time." At 1,800 yards 20% of the 12 pounders' ricochet shots registered hits while none of the direct-fire rounds struck (understandably, 6pdrs were apparently not fired); at 1,350 yards, the frequency of hits by 6 and 12pdrs was 0% : 8.8% for direct fire and 25% : 25% with ricochet; at 900-1,000 yards, the frequency of hits by 6 and 12pdrs was 8.3-12.5% : 11.1-16.6% for direct fire and 25% : 33% for ricochet fire. [26]
While the 12pdrs appeared to retain a marginal advantage, owing to the 6pdr's higher rate of fire the actual number of hits by 6pdrs at 1,350 yards in reality exceeded those by 12pdrs by 33%, while at 900 - 1,000 yards range, both calibres scored an identical number of hits. To the extent that an airborne cannon ball is lethal to the poor fellow(s) in the way, there does not seem to be much to distinguish the two calibres within normal engagement range! Which calls to mind Hughes' reference to the superior destructive power of British 18pdrs at Inkerman: is it possible that there is more to the story?
Although I am not familiar with the details of the engagement, Hughes notes that the Russian guns were on a ridge: if sloped steeply enough, that topographical fact would have much diminished any recourse by either side to effective ricochet fire. As for direct fire, the difference in effective performance between calibres, by extrapolation, does not seem to warrant a score of 100 : 0. Based on the above data, was even range a significant enough factor to distinguish so dramatically the performance of the two sides at 1,000 yards? Or were there other more important factors at play?
Point Black
Even at "point blank" range, simple physics shrank the distinctions between the differing calibres' ranges. Nosworthy explains the contemporary, technical meaning of the term as measured from a level barrel:
"Like a musket ball, the trajectory of the round shot was a parabola. After leaving the barrel, the round shot was forced above the line of sight, this latter being the straight line connecting the artillery piece and the target. The point where the round shot cut above the line of fire was known as the 'first point blank primitive'. Typically, this was immediately in front of the artillery piece. Pulled down by gravity, the cannon ball would soon cross back under the line of sight. This point was referred to as the 'second point blank primitive'. The formal definition of point blank fire, the one used daily by every artilleryman, was all fire directed at targets between the first and second point blank primitives.
"Direct fire referred to any aimed fire where the target was beyond the second point blank primitive but still within the effective range of the piece.
However, since the target was beyond the second point blank primitive (where it came down across the line of sight), it became necessary to elevate the artillery piece's barrel several degrees to obtain the needed range. This was the fundamental difference between point blank fire and direct fire." [27]
Based on Louis de Tousard's American Artillerists Companion on Elements of Artillery (2 vols., Philadelphia, 1809; vol. II, p.210), Nosworthy places the second point blank primitive at 384 yards for an 8pdr Gribeauval gun (2lb. Charge) and at 342 yards for a 4pdr Gribeauval gun (1lb. Charge). Nafziger's research on the Gribeauval System, on the other hand, places the point-blank range at 470 meters for a 12pdr, 460 meters for an 8pdr, and 440 yards for a 4pdr. The lesson from both authors is that whatever the specific range and relative charge, there was not an enormous practical difference between the point blank ranges of the different calibres of guns.
Interestingly enough, Nafziger's and Nosworthy's research seems to support simultaneously both notions of the effectiveness of different gun calibres: that 1) heavier guns were generally more "destructive" to the extent they maintained higher accuracy at greater ranges of direct fire and, owing to the weight of their shot coupled with velocity, possessed a greater penetrative power against solid obstacles such as earthworks, barricades, and walls, and 2) that the destructive effect of heavy and light guns on men and horses was not dramatically different within normal engagement ranges, further equalised by the latter's higher rate of fire.
So what led national ordnance boards to chose particular calibres of gun for service? Simple weight and manoeuvrability was certainly an issue. While horse artillery, generally equipped with the lighter, more mobile calibres, drew even short 12pdrs in French service, the British decided early on against encumbering themselves with a medium 12pdr battery in the Peninsula because of the poor roads. A belief that difficult terrain rendered heavier guns, such as 12pdrs, undesirable was not uncommon.
"In the mid-1790s, Generals Kleber, Desaix and Moreau sought to eliminate this calibre from their respective artillery parks. General Allix, the chief of staff of the artillery during Years II and III in fact had proscribed the use of the 12-pdr in the field." [28]
One might also surmise that smaller calibre guns had the advantage of lower comparative cost. Not only was there significantly less metal required in the construction of the barrel (less cost), but generally fewer assets were required to support smaller calibre guns. In French service, 4, 8, and 12 pdrs each required 1, 2, and 3 ammunition wagons to supply them, 4, 4, and 6 horses to pull them and 8, 11, and 15 crew to serve them; in Austrian service, 3, 6, and 12pdrs required 2, 4, and 6 horses each plus 11, 13, and 16 crew. [29]
Alexander Dickson, who eventually became Wellington's chief of artillery in the Peninsula, records that in 1809, von Rettberg's light 6pdr brigade (i.e., battery) required a total draught complement of 80 horses and 19 mules while Heise's heavier long 6pdr brigade required 93 horses and 29 mules to move: 22% more animals. [30]
By June 1810, he notes that Thompson's light 6pdr brigade was served by 89 gunners, and 54 drivers, and was pulled by 99 horses and 16 mules (the largest animal contingent of the three 6pdr batteries considered); Lawson's 9pdr brigade, meanwhile, carried 96 gunners and 83 drivers on its rolls along with 111 horses and 31 mules: 23% more animals for the heavier battery. [31]
In April 1811, he analysed the transportation needs of his two Portuguese artillery brigades, including not only the limbers, ammunition wagons, forges, wheel cars, store carts, officers' and NCOs' riding horses, and spare animals, but the batteries' reserve ammunition wagons, reserve spare horse, and the transport necessary for conveying six days of "corn, bread, and spirits" for the units, and determined that his 6pdr battery required 210 horses and 73 mules, while his 9pdr battery required 282 horses and 96 mules: 33% more animals. [32] Clearly, underlying direct and associated costs for heavier guns were markedly greater. I suspect I am not alone in wondering what a thorough cost-benefit analysis of gun calibre to battery cost might reveal.
Mobility vs. Combat
If mobility and cost favoured lighter guns, what about combat performance? I note that nowhere in Oman's seven volumes on the Peninsula War, neither in his text, ample quotations, footnotes, nor orders of battle, is gun calibre much dwelt upon. The general absence of reference by any of the chroniclers quoted in the opus tends to encourage one to imagine that the relative gun calibres were less important to the contemporary participants than readers (or wargamers) from a later age might have thought.
Surely, if relative calibres mattered greatly to contemporaries, one presumes that reference to the subject would have been unavoidable among the rich variety of contemporary quotations employed by Oman, if not referred to by the professor himself. Yet, his own discussion is quite devoid of such reference in either A History of the Peninsula War or Wellington's Army, 1809-1814. Nevertheless, Hughes points out in two of his books that there was, indeed, British concern about relative capabilities of guns:
"The British artillery began the Peninsular campaign with a standard armament of five light 6pdr guns and one light 5-1/2 inch howitzer in each horse artillery troop and each field brigade [battery].. The standard French field guns, their 8pdr, fired a shot weighing 8.8 British pounds and was superior in range and hitting power to the British 6pdr. As the campaign developed there was therefore a tendency to replace the light 6pdr with the 9pdr in the field brigades, and indeed to so the same in some horse artillery troops." [33]
Yet, again, Hughes' remarks dwell rather more on the difference in the weight of the respective shot than to specify the key advantage that was bestowed by weight: range. Between the elements of "hitting power" and "range", surely it was the latter that was upper-most in contemporary minds. In fact, the one distinction that is made on occasion in Oman is that between short and long British 6 pdrs, 60 and 84 inches respectively, according to George Nafziger's tables in Imperial Bayonets (while the 9pdr barrel was 72 inches long). [34] The longer barrel imparted greater muzzle velocity and thus greater range to the shot.
Reflective of the weakness of historians to happily nourish/repeat each other, rightly or wrongly, Nosworthy presents nearly identical information in Battle Tactics as that elucidated by Hughes on the British replacement of 6pdrs by 9pdrs, and is similarly oriented toward shot weight. While clearer about the benefit of greater range conferred, he clouds the issue immediately by referring to Müller's estimate, one drawn from Philip Haythornthwaite's Weapons and Equipments of the Napoleonic Wars, that "a 12pdr was twice as effective as a 6pdr, which in turn, was 50% more effective than a 3- pounder." [35] (Sound familiar? This statistic is also quoted above from Hughes' Firepower, p.32, and attributed to Müller, and also in Haythornthwaite's The Napoleonic Source Book, p.82). Once again, "effectiveness" rears its fuzzy head to leave the reader to puzzle out precisely what it means.
To Nosworthy's credit, however, he promptly forged onward to present a perspective I am surprised so eminent an authority as Hughes failed to raise in either Open Fire or Firepower: "Not all artillery officers felt that smaller ordnance was hopelessly out-classed by their larger brethren. Though larger pieces could fire further and provide greater punch, other factors were also relevant when the critical action occurred, that is, when the opposing forces were within 500 toises [1000 yards] (roughly 1,000 paces) of one another. A this distance, the enemy was within effective range of most ordnance found on the field. Moreover, in these cases the target was almost always cavalry or infantry.
Most of the projectile's kinetic energy was superfluous for the task at hand: the destruction of horseflesh and human matter. These officers argued that in the typical combat zone, defined as the distance within which most of the decisive manoeuvring occurred, a higher rate of accurate fire was much more important than the weight of shot or absolute range. Here smaller pieces could enjoy an approximately 3 to 2 advantage in the effect they could have on enemy troops." [36]
Indeed, commentators broadly concur that lighter guns could be loaded, aimed, fired, and run up again at a more rapid tempo than the heavier guns. Scharnhorst's trials referred to above empirically demonstrate the tendency of lighter guns to be able to fire more frequently, whatever the range.
To the extent that rate of fire was governed by the rapidity at which a gun could be run up again to its firing position after recoil, it is worth considering how far that could be. It appears that the distance could vary according to one researcher between 12 feet for a medium 12pdr (firing round shot at a 1'30 elevation with a 64 oz. charge) to a mere 3 feet for a heavy 3pdr (firing canister). [37]
The exact distance was evidently a complex result of gun weight, powder charge, and ammunition type (mass of shot), as the same research shows a light 6pdr recoiling 12 feet with a 24 oz. Charge, while a heavy 6pdr recoiled only 7 feet with a heavier 36 oz. charge (both firing round shot at a 1'30 elevation); the nature of the ground (soft, hard, sloped) would also have had a role. Then the gun crew had to contend with the sheer mass of the gun to be pushed back up to place.
One of Nafziger's tables [38] suggests total gun weights (barrel plus carriage) for French 4, 6, 8, and 12pdrs as 1505lbs, 2010lbs, 2525lbs, and 3440lbs respectively. By comparison, British short and long 6pdrs and a 9pdr (brass or iron is not specified) weighed in at 1737lbs, 2437lbs, and 3270lbs respectively. No points for deducing which gun was manhandled more easily. The comparative weights are also suggestive of a genuine need for larger crews at British pieces than at French.
Lighter and quicker to run back up to their firing position and laid with less physical effort, smaller calibre guns presented a less burdensome and exhausting task to gunners than that faced by their colleagues serving larger calibre guns (and wearying work it could be, witness Mercer's troop at Waterloo). Hughes does give a reluctant nod to this thesis when explaining why 18pdrs were unlikely to have been effectively employed at Waterloo in spite of the fact that "the destructive effect of the 18pdr gun was no less than 10 times as great as the 6pdr," noting, among other reasons, that "in defensive battle when the task of the artillery was to put the maximum number of rounds into the attacking enemy at short range, the higher rate of fire of the lighter equipments was probably a more important factor than the destructive power of a fewer, though heavier, shots." [39]
And in this, he contradicts his broad thesis that heavier guns had more destructive power; he tries to square the circle by attributing the difference between heavier guns' general destructiveness and the superiority of lighter guns' higher rate of fire to "short range". I might humbly suggest that while range is the key, it needs to be applied differently as an explanation.
When faced with counter-battery from a heavier battery, ". . . the textbook approach was to advance to within canister range. This would minimise the difference in calibres." [40] Indeed, Nafziger's research appears to suggest empirical evidence to defend the wisdom of such tactics. Nafziger cites six contemporary experiments (again under presumably optimal conditions) showing that 6pdrs demonstrated a capacity to supply as high a percentage of hits against a target as a 12pdr – up to the limit of the 6pdrs' customary effective range, after which their performance fell off substantially against the heavier guns. Sixpdrs scored an average number of hits versus the 12pdrs as follows: at 300 meters, 12.3% : 11.5%; at 375 meters, 9.5% : 8.3%; at 450 meters, 10.8% : 9.5%; at 525 meters, 6.9% : 10.1%; at 600 meters, 6.5% : 10.9%; while 12pdrs still scored 8% at 675 meters. [41]
As the reader may note, out to 450 meters, the 6pdrs actually scored marginally higher(!), although with such a low percentage of hits, it may be unwarranted to suggest a real superiority. While rate of fire and whether light or heavy canister was used is not indicated, the performance results do suggest that lighter guns were either as accurate as their heavier counterparts or, by firing more rapidly, able to put out an equivalent volume of destruction at a given range. Interestingly, the 12pdrs turned in a remarkably consistent hit average across all the tested ranges.
Apparent from the statistics is that the comparative advantage for the heavier gun lay in the range over which it could fire canister effectively. Other contemporary authorities support this. De Tousard's American Artillerist's Companion from 1809, cited by Nosworthy, gives outer effective ranges for heavy/light canister as 600/500 yards for 4pdrs, 700/600 yards for 8pdrs, and 800/600 yards for 12pdrs. [42] Nafziger cites the French artillerist, Col. D'Urtubie, as giving virtually identical maximum practical ranges for Gribeauval guns, in 1795, with somewhat shorter practical ranges (400 meters with light canister for 4pdrs, and 600 meters with heavy canister for 12pdrs). [43] In some instances, actual practice was modified by national battlefield experience: the British limited heavy case to 350 yards while other nations commonly employed it out to 500 yards [44] or to its maximum limit.
Thus, a 6pdr battery faced with canister fire from hostile 12pdrs at 700 yards appears to be well advised to consider closing the range to perhaps 600 or 500 yards so as to even the contest. To follow this example further, one can see how the simple attribution to heavier guns as having more destructive power might appear initially to be accurate. Yet, the comparative advantage is undependable: if the heavier battery could not sustain its distance and thereby safeguard the edge that superior range provides, the destructive advantage could be equalised between differing calibres.
The same appears to have held true with round shot. Whether employing direct or ricochet fire, heavier guns demonstrated in trials only a modest advantage or virtually none at all out to somewhere around 1,000 yards or so. Then, heavier guns again seemed to win a significant advantage at longer ranges as they were able to sustain greater accuracy in comparison to lighter artillery.
Hughes gives two well discussed examples of artillery performance at each end of the spectrum of gun calibres: British 12pdrs at Minden, in 1759, [45] and British 3pdrs at Talavera, in 1809. [46] I am not, with all due respect, convinced that he drew entirely correct conclusions. Hughes provides an example of British 12pdrs at Minden, engaged on a flank for some twenty minutes. Hughes numbers among the "special factors" which contributed to permitting a single battery of guns acting independently to achieve spectacular results, the gun weight of the ordnance involved: 12pdrs.
"They almost certainly would have been firing case shot at such short range. Each 12pdr case shot contained between 170 and 63 bullets, compared to 85 - 27 of the 6pdr's case, the exact number depending on the size of the bullets in which there was considerable variation. In the twenty minutes' referred to in [a letter by a gunner participating in the battle] each of the guns would have fired some 20 to 30 rounds, so that no less than 40,000 bullets would have been discharged at the French cavalry by Macbean's battery." [47]
Fair enough. But a light battery of 6pdrs could equally have been expected to fire approximately the same number of bullets: although firing roughly but half the quantity as that discharged by a 12pdr, a 6pdr could be reasonably expected to fire as much as, if not more than, twice as often! Presuming no hidden bias, might the real difference be one of range, different canister spreads, or lower velocity of the balls at impact - and thus lower lethality?
Capability
In another example of artillery's surprising capability, Hughes relates a story that rather seems to contradict his general thesis of the superior destructiveness of heavier guns. [48] Lawson's British battery of "little 3pdr guns," was located in an earthworks just in advance of the juncture of the British and Spanish positions. In spite of the reader's possible expectation of unexceptional performance, this battery went on to turn in remarkable results from its enfilading position to the left of Leval's assault, prompting one to wonder if perhaps "little" 3pdrs tend to be a bit under-rated. Hughes comments: "The additional losses that the guns could inflict were . essential, and had the further advantage that they could be caused before the attacker came to close quarters and could shake their nerve in advance." [49]
Among the lightest of field guns, the relatively more modest kinetic energy of either its shot or case bullets must have reduced its "penetrative" powers in comparison to even its weightier 6pdr cousin; nevertheless, within direct fire and then canister range of the attack for some thirty minutes and firing some 300 rounds, it penetrated the enfiladed French formations sufficiently to constructively contribute to the attack's repulse (although they share the laurels with several Spanish 12pdrs which joined them in the position).
So how does one judge the relative effectiveness of the different calibres of smoothbore field artillery during the Napoleonic wars? The purpose for which the artillery is to be employed clearly must be considered. For the penetration or destruction of physical obstacles, guns firing a heavier shot with greater muzzle velocity were more destructive and therefore clearly preferable.
"The 12-pdrs though less mobile, were very useful in destroying bridges or breaking down field fortifications encountered on the battlefield from time to time, such as redoubts and fleches. This was no mean contribution, since the failure to destroy such obstacles could delay an army's progress by one or two days and determine the success or failure of an operation or, under extraordinary circumstances, an entire campaign." [50]
Against unprotected enemy formations, however, comparative advantage seems more complex. The answer depends on how "effectiveness" is measured.
Nosworthy acknowledges that, "Any good artillery officer recognised that the true effect of artillery was in its ability to demoralise the enemy at a critical moment, rather than physically to eliminate the opposing force." [51] Although writing about smoothbore ordnance in the American Civil War, Paddy Griffith described heavy artillery's moral impact at "canister range":
"It was here that the flash and crash of the heavy [12pdr] Napoleons, firing two and a half pounds of powder with each detonation, could numb and stagger the enemy, even when they did not physically harm him. Certainly the shock power of such fire was of an altogether different magnitude than that of musketry." [52]
Quoting a Confederate officer's confidence that, ". . . strange as it may seem, [round shot] was much more efficacious for breaking a charging line than shrapnel or canister, which while disabling twice as many did not make such a crashing noise [Haskell., pp.67-68]", Griffith comments, "we find that a weapon's utility was proportional to its ability to impress and shock the enemy rather than its ability to kill him. Dead men did not run to the rear spreading panic and demoralisation among those not yet in range of the enemy's guns." [53]
This thunder factor surely counts strongly in favour of heavier guns' moral and psychological effect on the field. Griffith also perceptively identified another aspect of the moral impact: artillery's presence and anticipated destructiveness could dissuade an enemy from assaulting a particular part of a line where significant artillery assets were deployed and, by its own fire, thundering guns often provided moral support to other friendly units. Napoleon's early artillery chief, General Lapinasse, believed that, "the soldier who hearing the boom of these thunderbolts on the flanks of the army, is truly reassured.." [54]
If destructiveness is measured by casualties inflicted, however, heavier guns' superior comparable "effectiveness" is harder to judge definitively. The capacity of guns of differing calibres to inflict damage at a given combat range, with a given type of ammunition, seems to have been generally pretty similar. The key difference appeared at the margins of range: heavier guns could project canister and round shot to a greater distance. Thus, it was not so much a case of superior destructiveness inherent to heavier guns at a given range as over-lapping zones of destructiveness; heavier guns, by out-ranging lighter guns with either canister or round shot, seemed to have commanded zones (at the end of lighter artillery's canister and round shot limitations) at which the heavier guns' canister and then round shot could still be made effective, to the comparative disadvantage of the lighter ordnance. Within ranges at which the same munitions type could be employed, larger calibres appear not to have possessed an unqualified destructive edge.
Furthermore, against large enemy formations, the heavier gun's marginally greater accuracy at a given range was possibly only a modest advantage. Within normal combat ranges, most calibres of field artillery may actually have been more or less equally lethal.
Perhaps those little 3 and 4pdrs should be regarded with more respect. At least, from the perspective of the guy standing in their way.
[1] BP Hughes, Firepower: Weapons Effectiveness on the Battlefield, 1630-1850; Sarpedon, New York, 1997; p.29; Philip J. Haythornthwaite, The Napoleonic Source Book; Facts on File, New york,1990; p.391
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