Closing off the last post on 6-pdr field guns, I noted the Army was not completely satisfied with the Model 1835 6-pdrs. The issue was field handling. As the chart of 6-pdr bronze field guns demonstrates, the next model, designated by the design year of 1838, shaved fifty pounds off.
Most secondary sources deal with the reduced 6-pdr design with a reference to horse artillery. That was certainly a factor playing into the decisions made. In 1838 the Army also formed (or some would say re-formed) horse artillery batteries. The artillerists preferred smaller, lighter guns for that work. But other factors played into the preference for a smaller gun. For one, the ordnance officers noted that contemporary foreign field guns had dropped in length below 15 calibers (the ratio of the bore diameter to bore length).
However, in his Historical Sketch (see full title below in the references list), Birkhimer cites a report from the Ordnance Department dated February 20, 1840:
The patterns for the bronze guns are reduced somewhat in length for those established in 1835, so as to conform in length to the iron guns, for the purpose of allowing the later to be mounted upon the carriages established for the brass guns, simply by a small increase in the width of the roundels and the length of the assembling bolts.
The board’s comment alluded to the large number of older pattern iron guns (the Model 1827 and 1834 guns mentioned in my previous post, and other similar guns produced under separate contracts for the states and militia organizations). With new stock trail carriages (very much like the familiar reproductions seen today at Civil War battlefields) replacing the older block-trail carriages, the board anticipated the logistical problems. Once again, we see economy as a factor.
Overall the Board shortened the gun by about six inches. The length dropped from 15.7 calibers to 14 calibers. Although the base ring diameter, and thus thickness around the breech, remained the same, the overall weight dropped to 690 pounds.
This “shortening” of the gun was by no means just for the 6-pdr guns. Recall the Army also redesigned the 12-pdr field howitzer concurrently as the Model 1838 in that series, which was likewise a shorter version of previous models. All perhaps to the relief of the horses pulling the cannons, of course.
The Army turned again to Cyrus Alger and N.P. Ames to produce these light field guns. Alger’ contract accounted for sixty-two of the Army’s total requirement, while Ames delivered the remaining thirty-six. Both firms sold the same model to state and militia organizations, although not in significant numbers.
But in proofing and handling the Army found the Model 1838 unsatisfactory. In 1840, the Ordnance Board again redesigned the 6-pdrs, this time increasing the breech thickness. Ames delivered 27 of these “Model 1840” guns in 1840-41. Ames delivered at least one of the guns without a vent, presumably for what we might call “mock up” tests today. Another featured a 3-pdr powder chamber. Others were rifled after manufacture. These variants may indicate extended use of the Model 1840 as “trials” guns.
Like the Model 1838, the Model 1840 failed to measure up. At the same time, the ordnance officers conducted trials with various iron guns, apparently waffling over the choice of metal. In response to the February 20, 1840 report cited above, on March 5, 1840 the Secretary of War (Joel Roberts Poinsett at the time) responded:
The frequent attempts to adopt a system at once for the immediate use of our artillery, without an adequate acquaintance with the subject, have led to the protracted delay we have already experienced in this matter. The Secretary is therefore opposed to all temporary expedients. The patterns presented for approval, in conformity with the proposals, are confessedly defective, and have been devised because the material is supposed not to be good or the knowledge of the foundries imperfect. The weight is not considered material, but the length is very objectionable…. From a desire to use the same carriages, the bronze gun is likewise reduced, extending these serious objections to all the light artillery, whether iron or brass.
So in one passage, Secretary Poinsett puts an end to half measures. He called for the board to drop the “backwards compatibility” requirement. There will be a single pattern advanced from this, which we know of course as the Model 1841 6-pdr Field Gun. But before turning to the Model 1841, I need to first address some of the tests and trials alluded to in the Secretary’s letter. As we shall see, a lot of thought, reason, and science went into the final gun design.
Aside from on site notes and links provided above, sources consulted for this post were:
Birkhimer, William, Historical Sketch of the Organization, Administration, Material and Tactics of the Artillery, United States Army. Washington: James J. Chapman, 1884. Particularly pages 275-9 discussing the evolution of the American systems of artillery.
Hazlett, James C., Edwin Olmstead, and M. Hume Parks. Field Artillery Weapons of the Civil War, Revised Edition. Urbana and Chicago: University of Illinois Press, 2004.
Ripley, Warren. Artillery and Ammunition of the Civil War, 4th Edition. Charleston, S.C.: The Battery Press, 1984.