Canister receives an undue level of importance if you ask me. We often hear canister described as “a big shotgun blast” that dominated the battlefield. And the greatest combination, as often cited by those offering this view of battlefields swept clean by canister, was when the projectile belched forth from the 12-pdr Napoleon. Oh, the power of the mighty canister round!
Well, let me offer the observations of an authority on the subject, Brigadier-General Henry J. Hunt:
There is much complaint of the inefficiency, at close quarters, of the canister for the light 12-pounder gun, owing to the small number of balls it contains. This effect was made apparent at Gettysburg, and is complained of frequently now that the batteries of these guns in the horse artillery often come in close contact with the enemy’s cavalry and infantry. The present canister shot is so large as to be effective at long ranges, so long that it would be better to use shrapnel.
I respectfully request that canister with a smaller ball, say of 2 to 3 ounces–or if of smaller diameter than that of a 2-ounce iron ball, then one of lead–may be furnished at as early a day as practicable, in sufficient quantities to furnish at least the horse artillery with one-half their canister of the new pattern. These canisters would carry from 60 to 80 shots, and would probably be much more effective within 200 yards than the present 7-ounce ball of 28 to the canister.
Hunt wrote this in a letter to Brigadier-General William F. Barry on October 26, 1863 (making it a nice sesquicentennial moment for the moment, if you will). At that time Barry was Inspector of Artillery, commander of the Artillery School of Instruction, and former Chief of Artillery for the Army of the Potomac – a position that Hunt held when the letter was written. In short, Hunt offered these observations – not to some ordnance officer who’d never gotten a whiff of the battlefield – rather to a slightly-senior peer, and someone who also had practical experience in these matters.
What Hunt describes is a tactical employment problem with a weapon design. Canister, because of the sub-projectile ballistic properties, was not as effective as expected in the critical range under 200 yards. Consider 200 yards the “red zone” for artillery. At that range, infantry battle line musketry, particularly volley fire, begins to be so effective that the artillery cannot counter at a normal rate of fire. And certainly artillery had little chance at standing unsupported when the ranges closed under the 200 yard range.
Yet, as Hunt complained, the ballistic qualities of the standard 7-ounce iron balls (yes, damn it, iron balls, not lead musket balls) was insufficient to hold back, much less sweep away, advancing infantry at that range. There simply were not enough sub-projectiles to do enough damage. And the range where the canister was worth using, which I’d read into what Hunt wrote and say was between 200 and 400 yards, the experienced artillerist preferred case shot (shrapnel, in his words).
And… oh… by the way… case shot DID have lead musket balls to scatter about. A 12-pdr case shot held, by regulation, 76 of those musket balls. Or, in other words, about the same amount of sub-projectiles Hunt wanted to see in a canister round.
Muzzle velocity of a 12-pdr Napoleon was somewhere around 1400 feet per second. Range tables for the gun list case shot as having a range of 300 yards, when the gun was at near zero degrees elevation, and time of flight was one second. The standard Bormann Fuse of the time had a minimum burn time of ¾-second.
Let’s do the math. So when facing an advancing infantry formation, a really good gun crew might get off a case shot at, say, 400 yards scattering 76 sub-projectiles (not counting the parts of the shell itself, but let’s stick to the basics here); then another at 250 yards dispersing another 76 sub-projectiles; but the next shot would be canister at 150 yards or less putting out a paltry 28 projectiles. Do you see the problem that Hunt was complaining about?
The simple fact is that canister was not the projectile of preference for artillerists. Nay, that selection was only made in desperate situations. That’s why a standard 12-pdr Napoleon ammunition chest carried only four canister, compared to twelve case. Artillery was supposed to hold the enemy at greater than musketry range, not stop bayonets by spitting out a couple dozen little iron balls at close range.
I’ll step down from my limber chest. Have a great Friday!
(Citation from OR, Series I, Volume 29, Part II, Serial 49, page 391.)