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[Civil War] 12-pounder Napoleon Gun-Howitzer development

I found this letter in the National Archives in the 1980's and always intended to build an article around it. I'm fairly sure this information has never been published. When I found the letter among other somewhat unrelated material, it was folded crisply in thirds, on blue watermarked paper, brown at the edges. It was bound along the seam with a pink ribbon which was ironed flat and obviously had never been removed to allow copying (until I removed it after receiving permission.) I only sent out two copies after I found it, one to my late friend Edwin Olmstead, a Company Fellow, and one to the management at Fort McHenry.

The letter is important because it describes Mordecai's reasons for altering the design of the famous 12-pounder "Napoleon" of Civil War fame. The original Napoleon, apparently the very one which Mordecai tested at Fort McHenry, is on display at the Petersburg National Battlefield Park, VA., in the visitor's center (or was last time I checked.)

The topic of Maj. Alfred Mordecai and his huge contribution to the development, refinement, and standardization of U.S. Army ordnance is beyond the scope of this posting, but the text of this letter will give you some insight into his genius.

I've transcribed the letter except for a few words I could not make out, indicated by ????. A doubtful word is followed by (?). Underlining which I faithfully copied from the letter was somehow lost when the file was saved, as was the precise paragraph and subparagraph indentation which I copied from the letter. The tabular data is provided as links to images.

(Mordecai to Craig)
May 25, 1857

In pursuance of your instructions of the 18th inst, I attended the trial of the new 12-pdr gun at Fort McHenry. I have the honor to make the following report:
The gun was tried under the direction of Lt. Col. Horace Brooks, 2nd. Arty, commanding at Fort McHenry, & in presence of a Board of officers consisting of:

Major Reynolds, 3rd. Arty

“ French, 1st “

Capt Phelps 4th “

“ Barry 2nd “

It was mounted on a 24-pr howitzer carriage not of the latest pattern, but not differing materially from it in point of strength. The axis of the trunnions is immediately over the axis of the axle tree, when the gun is in battery; the length of the gun required a slight alteration in the position of the elevating screw, as adjusted for the 24-pdr howitzer.

May 16th. The gun was maneuvered along with a 6-pdr. Gun, by Major French, on the usual drill ground within the wall enclosing the public land; the ground had become heavy with rain of the two preceding days. The limber chests were not loaded; the pieces were harnessed at first with four horses and then with six to each. There appeared to be very little difference in the facility of movement of the two pieces.

May 18th. Col. Brooks put the 12 pdr gun in battery with two 6-pdr & a 12 pdr howitzer, all harnessed with 4 horses (limber chests & caissons empty) & maneuvered them on the usual morning drill over the ground within the wall. In the course of the maneuvers the battery was driven across the steep embankment, about 6 feet high, on which the road runs. The movements appeared to be very little retarded by the presence of the 12-pdr gun, except that a greater effort of the men was required in working the piece by hand, changing front, or advancing and retreating without the limber; still the men did not complain of too great exertion & the horses were not perceptibly more distressed than with the 6-pdr guns. After the drill the gun was fired a few rounds to see the recoil & the effect on the carriage .i.e. none of the guns have locks on them and friction primers only were used. To try their efficacy, some blank cartridges were first fired:

1-12 pdr blank-cartridge not pricked

2-the same

3- “ choked end at the bottom & seam up; cartridge not pricked

4-6 pdr cartridge, in the same way

5-6 pdr “ with a 12 pdr bag over it, not pricked

6-“ “ with two 12 pdr bags “ “ “

7-“ “ three “ “ “, choked end of cartridge down
There was no failure to fire the charge.
The gun was placed on a grassy piece of ground nearly level; there being no good range for target practice, the shots were fired over the water.

1-With shell, at greatest elevation, recoil 8 ft.

2-Sph. Case, about 3 degrees. Recoil 10 ft. 6in.., fuse 4 Ύ sec., shell struck the water too soon, did not burst

3-Sph. Case. Recoil 10 ft. 6in, fuse 4 Ύ sec.,, burst well.

4-Solid shot, no elevation, recoil 15 ft. 4in..

5-Canister, elev. 1 degree, recoil 11 ft 10in.

6-“ “ “ “ 11 ft. 4in..

7-Sph. Case-1 primer failed. Recoil 11 ft. 4in.., fuse 2 sec., good

8-Canister –Recoil 12 ft.

9-Sph. Case- “ 10 ft. 7in.. , fuse 3 sec., burst short

10-Shell “ 9 ft. 5in., “ “ good

11-shell “ 8 ft 6 in, “ 4 sec good

12-shell ‘ 9 ft 4 in., “ 4 Ύ good

The guns all moved closer to the edge of the water, trail a very little up hill.

13-solid shot, 1 ricochet-recoil 13ft 7in.

14- “ “ 6 “ “ 14ft

15- “ “ greatest elevation 10ft 6in.

16-canister-1 tube failed. 10ft 4in.

Four rounds were fired from 12-pdr. Howitzer with shells, recoil 4 ft 3in., 1 primer failed, tube bent on account of vent being enlarged and battered with lock. Five rounds were fired from 6 pdr gun, with canister, recoil 4 ft. 5 in.

The shots on the water showed very plainly the great effectiveness & superiority of the 12 pdr. Canister. The firing with the new gun was not continued further, because it was thought better to use the ammunition at some other place, where the range and effectiveness of the shot could be observed.

May 20th. After about 36 hours of heavy rains, the 12 pdr gun and a 6 pdr were taken out into low, wet ground, to be maneuvered. The limber chests were regularly packed with ammunition; 12 shells were put, instead of as many shot, in the 12 pdr limber. The carriages were tried, with 4 horses, & with 6, to each; the difference in the draft, between the 12 pdr and the 6 pdr was so unimportant that in coming up the steep muddy bank, the 6 pdr with 4 horses was stalled where the 12 pdr with the same number of horses, had passed, the skill of the drivers & a little difference in the teams compensating for the additional weight of the gun and carriage, which is about 600 lbs. The ground was so soft that in firing 3 rounds with shot, the 12 pdr wheel was buried nearly half the length of the spoke, & the 6-pdr, nearly as much. In trying to work the piece around by hand, under these circumstances, the handspike of the 12-pdr was cracked at the socket, by the effort of two men.

From these exercises, I infer that, with a little experience and practice on the part of the men, this 12 pdr gun could be maneuvered, with all the requisite facility, in field batteries. For rapid & long continued movement, & in active service in war, it would require 6 horses; but that number has been found necessary, under those circumstances, even for 6-pdr batteries, & I think it would be sufficient, for the 12-pdr, as the draft of each horse, with 3 men on the limber, would not exceed 700 lbs.

Some little changes may be suggested in the model of the 12-pdr gun which would facilitate its service in battery. The preponderance of the breech, & the consequent effort to raise the trail from the ground are unnecessarily great. To change this I propose to add 3 inches to the length of the piece & to place the trunnions half an inch further to the rear; this would make both the whole weight & the preponderance to agree nearly with which was at first intended; the carriage would be easier to handle & the recoil would be a little reduced, whilst the additional weight would be unimportant. The operation of dismounting & mounting the gun by hand, with no other implements than the handspikes, was tried & performed without difficulty. The changes of dimensions necessary for this change of preponderance are marked, in red ink, on the original drawing of the gun in our office.

I have remarked that the 24-pdr. howitzer carriage does not answer for this gun without a slight alteration in the position of the elevating screw – with these new dimensions that alteration will be still greater, & another change is also required, in the position of the trunnion holes; these should be nearly over the axle trees in the carriage tried at Fort McHenry, instead of being 1 in. in rear, as in the 24 pdr howitzer carriage. The length of the cheeks would thus have to be somewhat reduced & the rear assembling bolt brought forward, so as not to weaken the stock by having it too near the hole for the elevating screw. These changes would make a special carriage for the light 12-pdr gun. The dimensions of the stock & cheeks, I believe to be sufficiently large for this gun, in comparing it with the 24-pdr howitzer, & with the carriage for the new French 12-pdr gun. I propose however to leave the length of the trunnions as at present (1/4 in. longer than the thickness of the cheek) in case it should be found expedient to increase that thickness.

In order to enable you to compare this new 12-pdr more readily to the new French light 12-pdr, which is used by the horse artillery is their 8-pdr gun bored up to 12 pdr; you will observe that the charge of powder is reduced & few solid shot are used with it.

[links to images of tabular data which appear at this point in text of letter]

By this statement it will be seen that as regards the strength of gun & carriage & their mobility, the new gun proposed compares favorably with the new French canons-obusiers, for the field, & may be considered equal to the other in all respects, except in the diameter of the bore & the consequent greater weight of the French shot & ammunition. This comparison is important, because the French guns have been somewhat tried in the field, during the Crimean campaign. Their field artillery was armed entirely with these pieces, the horse artillery batteries having the light guns (8 pdr bored up,) and the foot batteries, the new pattern.

The question of substituting the 12-pdr for other field batteries in our own service is not perhaps within the purpose of my report, but I may remark that our object at present should be rather to arrange the details of the 12-pdr batteries for use in case of need & to give the artillery the opportunity of trying them & ascertaining the range & etc. of the guns. Considerations of economy may induce us to retain the 6-pdr batteries for ordinary practice, as being sufficient for exercises in driving & maneuvering, requiring fewer horses & being less costly in all respects; whilst for frontier service they have the advantage of lightness & of carrying a greater quantity of ammunition.

I would therefore suggest making at present not more than four of the new guns & mounting these on carriages modified as above mentioned, with caissons suitably arranged for the altered proportions of ammunition. Two of these pieces may be sent to Fort McHenry, to be used in maneuvers & firing, & two others to Fort Monroe, with a good supply of ammunition for trying the endurance of the guns & carriages, & making tables of firing at the same time. The gun now at Fort McHenry with its carriage & caisson should be withdrawn, to avoid any confusion in using them with the new ones.

I add some remarks in defects in the artillery equipments which I noticed in the drill or which were pointed out to me by the artillery officers.

In the carriage sent to Fort McHenry for the 12-pdr gun (which as I have said is not of the latest pattern for 24-pdr howitzers) the wheels do not fit well on the axle, having too much play between the shoulder & linch (?) washers; the sponge & rammer chain is too short to hook up, being made for the 24-pdr howitzer which formerly had a 9-pdr chamber. The lock chain has no toggle, but a simple hook. The straps on the limber chest are put on wrong; the short strap being on the rear of the box, which is the front of the limber, the buckle comes under the gunner’s seat & is inconvenient; the rule (?) for the front & rear straps given in the ordnance manual p. 305, should be reversed, if the terms front & rear are applied to the chest & not to the limber.

The prolonge is not adapted to the drill as laid down in Artillery tactics; one ring should be left off & care should be taken that the toggle will go into the eye of the lunette, which is not always the case.. The drill provides for a movement to the front with the rolonge, but there is no place to attach it to the front of the carriage.

Harness: The hames ???? soon wears out or breaks; this is owing to the twisting strains which is brought on it by the pulling of the lead horses, in consequence of the trace chain not ??????ing freely through the hames lug(?), the arrangement was intended for rope traces(?), with which this inconvenience did not occur; the evil is quite a serious one & should be remedied by a modification of he lug(?); all those in Major French’s harness, sent to him, last year from Allegheny arsenal, have been repaired(?).

The bridle bit is not well shaped & the brass plating is badly done & soon rubs off. The spiral curl in the ????? of the cheek piece not only adds nothing to the strength of the bit, but it catches in the horse’s lips & even in the next horse’s bit, as I witnessed one drill. The officers use the dragoon bit, which is also brass plated, but of simpler form. They find the curb bit disadvantageous for the off horse & think a well-made snaffle would be better; we formerly had a snaffle for the off horse & it is used in much of the European services.

Linch Pins The round linch pin, rubbing against the washer, is soon worn flat & weakened & the leather holder s apt to be out by the jerking of the linch pin & the pin jolted out & this has often occurred in rapid movement on paved roads & I observed that a wire had been substituted for the leather. I would suggest the experiment of putting lugs on the outside o the linch washer to prevent it from turning & thus to save the linch pins.

The hasp & eye plate for sponge & rammer chain is objected to, as not being readily fastened up & causing delay. Major Ringgold had a toggle and plate like that which holds up the pole yoke. Major French mentioned the Sardinian plan mentioned in Major Hagner’s report (1848). This is simple and easily used, & may be worth a trial.

The lanyard hook for friction primers should be made larger, so that the eye of the hook will receive 2 shrouds, or a larger lanyard.

Friction Primers. It will be observed in the report of firing that several primers failed. The failures were 4 in 40 rounds. One of them is to be attributed to the enlargement & battering of the vent, causing the tubes to bend & the wire to break. One was caused by he wire drawing out, without igniting the powder in the tube. . The primers fire with great force, as seen in the trials with several thicknesses of cartridge bag stuff over the powder. Great care is required in annealing the brass wire, so that it shall not break in straightening – could not copper wire be used?


Yr Obd Servt

(signed) A. Mordecai
Major, Ordnance

Source: Alfred Mordecai, Major, Ordnance, U.S.A. to H.K. Craig, Colonel, Ordnance Department, Washington, May 25, 1857, file EX-1a-210, Record Group 156, National Archives Building, Washington DC

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[Civil War] 12-pounder Napoleon Gun-Howitzer development
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Canon obusier de campagne de 12 modele 1853
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