I brought up a point yesterday regarding the weight of the 24-pdr Field Howitzer compared to the 12-pdr Light Field Gun (Napoleon), and how those numbers factored into tactical mobility. Because I like the “cold hard numbers,” I’ll offer up the planning factors here which back that conclusion.
The US Army, having great experience with horse-drawn artillery, had by the time of the Civil War a very realistic set of guidelines for the employment of the weapons. Particularly detailing the load each horse could stand to draw. From the 1864 Instruction for Field Artillery, page 33:
Artillery horses are required for quick draught; they should move the carriage, ordinarily, rather than by the weight thrown into the collar than by muscular exertion.
Description. — Age at date of purchase, 5 to 7 years; height, 15 hands 3 inches, allowing a variation of 1 inch. They should be well broken to harness, free from vice, perfectly sound in every respect, full chested, shoulders sufficiently broad to support the collar, but not too heavy; full barrelled, with broad, deep loins; short coupled, with solid hindquarters; and their weight as great as is consistent with activity, say from 1,100 to 1,200 pounds when in good condition. In purchasing, special attention should be directed to the feet, to see that they are perfectly sound and in good order, with hoofs rather large, and that the horse submits willingly to be shod.
Long- legged, loose-jointed, long-bodied, or narrow-chested horses should be at once rejected, as also those which are restive, vicious, or two free in harness.
A draught horse can draw 1,600 pounds 23 miles a day, weight of carriage included. Artillery horses should not be required to draw more than 600 pounds each, including the weight of the carriage, but excluding that of the cannoneers.
A horse travels the distance of 400 yards at a walk in 4 1/2 minutes; at a trot in 2 minutes; at a gallop, in 1 minute. He occupies in the ranks a front of 40 inches, and a depth of 10 feet; in the stall, a front of 5 feet; at the picket, a front of 3 feet, and a depth of 9 feet. Stalls for artillery stables should be 6 feet wide.
Germane to the discussion of weight, regulations called for horses between 1100 and 1200 pounds, expected to pull 1600 pounds. That translated to, as noted in the regulations, 600 pounds of payload per horse. For computations, assuming the cited weights of the horses, the payload variance is 600 to 650 pounds (figuring although smaller horses allow more weight in the 1600 pound top end window, such horses have less “horse power”). Thus for planning purposes a six-horse team’s expected payload was between 3600 and 3900 pounds. An eight-horse team’s expected payload was between 4800 and 5200 pounds.
I would caveat this by saying the practical payload, based on the regulation’s wording, was the lower figure. I’ve included the higher figure here as the reasonable high-end limitations. Simply put, a six-horse team SHOULD easily pull a 3600 pound load, and accommodate a few hundred extra pounds up to 3900, but the more weight, the more easily were the horses fatigued.
Given that expected payload, consider the weight of gun, carriage, limber, chest, and assorted equipments for each type of gun. The manual of 1864 lists those as such (page 15):
- 6-pdr Field Gun – 3,185 lbs
- 12-pdr Light Field Gun (Napoleon) – 3,865 lbs
- 12-pdr Field Gun – 4,457 lbs
- 12-pdr Field Howitzer – 3,214 lbs.
- 24-pdr Field Howitzer – 4,036 lbs.
- 32-pdr Field Howitzer – 4,575 lbs.
I would further add the expected weights for rifled guns not mentioned in the regulations:
- 3-inch Ordnance Rifle - 3,120 lbs (1)
- 10-pdr (2.9 and 3-inch) Parrott Rifle – 3,190 lbs (1)
- 3.80-inch James Type 2 Rifle -3,215 lbs (1)
- 20-pdr Parrott Rifle – 4405 lbs (2)
- 30-pdr Parrott Rifle – 8000 lbs (3)
- 4.5-inch Siege Rifle – 7300 lbs (3)
Note 1: The 3-inch Ordnance Rifle, 10-pdr Parrott, and James Rifles used a modified 6-pdr Field Gun Carriage with a 12-pdr Field Gun axle.
Note 2: The 20-pdr Parrott used a modified 32-pdr Howitzer carriage.
Note 3: The 30-pdr Parrott and 4.5-inch Rifle used a siege & garrison carriage similar to the regulation 18-pdr Siege & Garrison Gun. The arrangement did not include an ammunition chest. For calculations I have added the weight of the gun and implements to the weight of the carriage specified in the Ordnance Manual of 1862, page 76.
Of course as mentioned in my long-winded study of the James Rifle, the Type 1 James was patterned off the standard 6-pdr Field Gun, and weights thus followed closely.
Caissons weights cited in the regulations were:
- 6-pdr Field Gun – 3,493 lbs
- 12-pdr Napoleon – 3,811 lbs
- 12-pdr Field Gun – 3,856 lbs
- 12-pdr Field Howitzer – 3,868 lbs
- 24-pdr Field Howitzer – 4,051 lbs
- 32-pdr Field Howitzer – 3,811 lbs
Cross referencing the payloads for six- and eight-horse teams the breakdown is such:
Six-horse team – 6-pdr Field Gun, 12-pdr Light Field Gun (barely), 12-pdr Field Howitzer, 3-inch Ordnance Rifle, 10-pdr Parrott, James Rifle, and all types of caissons except that for the 24-pdr Field Howitzer.
Eight-horse team – 12-pdr Field Gun, 24-pdr Field Howitzer and respective caisson, 32-pdr Field Howitzer, and 20-pdr Parrott.
Other arrangements were required for the 30-pdr Parrott, 4.5-inch Rifle, and any of the siege guns or howitzers. In some cases just eight horses, with the rate of march justifiably slowed.
And to this discussion I would further add consideration for the number of rounds brought to the gun-line with each ammo chest:
6-pdr Field Gun – 50 rounds x 4 chests = 200 rounds
12-pdr Napoleon – 32 rounds x 4 chests = 128 rounds
12-pdr Field Gun – 32 rounds x 4 chests = 128 rounds
12-pdr Field Howitzer – 39 rounds x 4 chests = 156 rounds
24-pdr Field Howitzer – 23 rounds x 4 chests = 92 rounds
32-pdr Field Howitzer – 15 rounds x 4 chests = 60 rounds
3-inch Ordnance Rifle and 10 pdr Parrott – 50 rounds x 4 chests = 200 rounds
20-pdr Parrott – 25 rounds x 4 chests = 100 rounds
Thus given firing rates and other tactical considerations, the Napoleon could stand on the line about one-third again longer than a 24-pdr howitzer. And required 12 horses to service one gun, opposed to 16 with the howitzer.
Other factors to consider here, of course, are:
- Weight of the projectile: More “bang” on the target means more damage to the enemy.
- Range of the projectile: If line of sight allowed, gunners preferred longer ranges, particularly for counter-battery fire. Shot and shell were the preferred rounds. If the battery was using canister, something was probably going badly!
- Accuracy of the piece: Less rounds required for the knockout, particularly with counter-battery fire.
- Ease of service: The heavier the projectile the harder the piece is to load. Heavier the gun, the harder the piece is to position, reposition, and adjust.
- Physical footprint of the gun in action: Sort of a tip of the hat to Fred Ray here, as the more horses and soldiers milling about makes for more targets. Artillery batteries were often rendered unserviceable due to incapacitated horses. As Fred points out, batteries were often the selected targets of sharpshooters on the battlefield.
- Durability of the piece: Obviously a gunner did not want the piece bursting in action, nor did the crew want the gun to wear out quickly (rifling wear, bore enlargement, or vent erosion).
The baseline requirement for the Civil War artillerist was getting a cannon offering the heaviest projectile to the best possible range, supported by the most amount of ready ammunition, and requiring the least amount of horseflesh to move about. I’ve always felt the 12-pdr Napoleon closest met that requirement, but the 3-inch Ordnance rifle ran a close second. In those days before mechanized warfare, tactical limitations were often measured in pounds and feet, translating to sweat and brawn in implementation.