Discussing the initial organization of the artillery within the Army of the Potomac, I offered an overview of the plan proposed by General William Barry, and approved by General George McClellan. Again, there are some detail differences between Barry’s reports of August 1861 and September 1862. One of those, although small, appears in the first detailed point provided by Barry – the ratio of artillery pieces to troops.
In August 1861, Barry feared the poor discipline of the volunteer infantry force. Thus he recommended, “…the artillery, to give them confidence and steadiness, is arranged upon the basis of three pieces to 1,000 men.” He later predicted that ratio might drop by half as the troops gain in experience. Thus the number of guns Barry desired for the army at Washington, D.C. was initially around six-hundred, but was willing to lower that figure to three-hundred to support a 200,000-man army. (OR, Series I, Volume 5, Serial 5, p. 580)
But in September 1862, Barry would write, “That the proportion of artillery should be in the ratio of at least two and a half pieces to 1,000 men, to be expanded if possible to three pieces to 1,000 men.” (OR, Series I, Volume 5, Serial 5, p. 67)
For comparison, the Instruction for Field Artillery (which recall Barry was a co-author) offered:
The proportion of field artillery to other arms varies generally between the limits of 1 and 4 pieces to 1,000 men, according to the force of the army, the character of the troops of which it is composed, the force and character of the enemy, the nature of the country which is to be the theater of the war, and the character and object of the war. Similar considerations must regulate the selection of the kinds of ordnance, and the proportions of the different kinds. (Instruction for Field Artillery, 1864 edition, page 3)
I conclude Barry was practicing exactly what he preached with regard to the ratios. But honestly, I’ve always scratched my head at Barry’s offered ratios. Based on a 3-to-1,000 ratio, a six-hundred gun artillery park would support a 600,000 man army! McClellan’s dream!
However that number does seem more to scale if Barry was discussing the proposed number of guns for the entire army, and not just the Army of the Potomac. I’ve never attempted to estimate the number of guns the Federals needed in the fall of 1861. I would offer that by my figuring the whole Federal army needed around 950 guns by the fall of 1862 for the major armies, and at least a hundred more by the summer of 1863. So perhaps 600 guns would be a good start.
Barry’s 1862 report offed some interesting figures comparing the artillery with the Army of the Potomac up to that point. In July 1861 the “new” Army of the Potomac had thirty guns in nine batteries (imperfectly-equipped batteries as Barry notes). In March 1862, Barry put the numbers at 520 guns in 92 batteries around Washington. The Army of the Potomac moved to Fort Monroe in April with 299 guns in 52 batteries. That increased to 343 guns in 60 batteries by the Seven Days in late June.
Consider that in September 1862 the Federal fought Antietam with 293 guns in 57 batteries (30 guns in another seven batteries were in the area but not engaged), supporting 75,000 troops – a four guns to 1,000 men ratio. And in July 1863, when many would say the Army of the Potomac was at its peak of efficiency, training, and experience, it fought Gettysburg with 372 guns in 67 batteries, supporting 70,000 troops – over five guns for every 1,000 men.
My conclusion, based on the raw numbers deployed in the later battles, is that Barry’s ratio of three guns per 1,000 “green” troops was too low.