Field artillery mobility and the labor of a horse

Think I’m being harsh to say Jackson’s artillery was immobile in February 1863?

I’ve discussed the importance of horses to the Civil War artillery a number of times.  Maybe this is an axe I like to grind, but my sense is some overlook the practical considerations of horse drawn artillery while interpreting tactical and operational (arguably even strategic) movements.  Artillerists of the Civil War planned movements with the ability of their animals in mind.  That translated to considerations at the division, corps, and army level as to the rate of march.  The rate of march derived from the practical weight a horse could draw.  John Gibbon expressed it well in his Artillerist’s Manual:

A horse of medium strength can draw a load of 3,000 lbs. from 20 to 23 miles per day, over a paved road, and about 1,900 lbs. over a macadamized road.  This includes the weight of the carriage.  From 1,500 to 1,600 lbs., not including the weight of the carriage, is therefore a proper load for a horse over ordinary roads; and in case rough, broken ground is to be passed over, he should not be required to draw more than 1,100 lbs.

A horse moving at a trot can draw at the same rate as above, a weight of 800 lbs., not including the carriage, the weight of which would bring the load up to about 1,100 lbs. These numbers comprise the maximum load; and if the carriage is to move at a trot across fields, or in the open country, the weight, including everything, should not exceed 733 lbs.; or, if the carriage is not well constructed, 600 lbs.

Given the advice from “He who limps”, as the Nes Perce would later call Gibbon, how mobile were Jackson’s batteries that February?

Line engraving of a field gun on a limber used...
Field Gun and Limber

Let’s look at Pegram’s Battery (Purcell Artillery).  At that time the battery had two 10-pdr Parrotts and two 12-pdr Napoleons, ranking it as one of the better equipped in the army. Given standard arrangements for batteries, Purcell Artillery had four guns with limbers and eight caissons.  The report indicates the battery had two four-horse wagons.

The report indicated the battery had 45 serviceable and 12 unserviceable horses.  I won’t second guess Lieutenant Dandridge here.  If he said the animals were unserviceable, that would indicate the battery could not rely upon them (SPCA commentary aside, if the horse was unserviceable it could not take the weight and it shouldn’t be in the team).  Taking the maximum load factors (generously using the 1,500 pound per horse figure) from contemporary manuals, the horses of Pegram’s Battery could draw a total of 67,500 pounds.

Line engracing of a caisson used in American C...
Caisson and Limber

Sure, 67,500 pounds sounds like a lot.  But how much “stuff” did the Purcell Artillery haul around?

  • Two 10-pdr Parrotts with limbers at 3,190 lbs. = 6,380 lbs.
  • Four 10-pdr Parrott caissons at 3,493 lbs. = 13,972 lbs.
  • Two 12-pdr Napoleons with limbers at 3,865 lbs. = 7,730 lbs.
  • Four 12-pdr Napoleon caisson at 3,811 lbs = 15,244 lbs.
  • Two four horse wagons estimated at 3,600 lbs = 7,200 lbs.

That totaled 50,526 pounds.  So shouldn’t Pegram’s battery have a “reserve” of horsepower there?  Not so fast.  How are the gun crews getting to the battle?  Riding horses or riding on the ammo boxes?  Let’s go back to Gibbon again:

A horse carrying a rider, loses his power of drawing in proportion to the increase of gait.  This diminution, which is about ½ when the horse is at a walk, becomes ⅔ when he trots.  Thus a team of 5 horses with a single driver seated on the carriage, will draw more than 6 horses, two of which are mounted with drivers.

In artillery carriages, half the horses carrying drivers, a team of six horses, moving at a trot, actually experiences a loss in traction of 3 x ⅔, or two horses.

So, where would you put that artillery crew?  Manuals of the day figured the average soldier weighed 180 pounds when equipped (today?  heh!).  So 111 officers and men present in Pegram’s Battery at that time would translate to another 19,980 pounds.  The total  “weight” of the battery was then 70,506 pounds.  Yes, tipping the scales against the horses.

The practice of the time was to place some of the crew on the boxes while others road the spare horses.  That would allow for some rotation of mounts and allow some rest cycles.  But to haul four guns, eight caissons, and two wagons, the Purcell Artillery needed 80 horses.  Not enough to properly outfit the teams, much less to have spares for rotation.  Indeed, if we count “seats” on caissons and limbers, there’s a shortfall of space there too.  So many of those artillerists would be walking.

Line engraving of a battery wagaon and portabl...
Battery Wagon and Forge

What’s the pace of a “foot” battery?  I’m not sure the manuals of the day provided a number, but certainly slower than a mounted battery.  Given the shortfall in horsepower and the slower pace, could Pegram’s Battery move from winter quarters to a threatened point?  Probably.  In a timely manner?  Now the answer requires qualifiers.

There’s no doubt that had Jackson of called upon Major-General A.P. Hill, and in turn Hill called upon the men of the Purcell Artillery, to move that winter, the men would have responded with all possible effort.  But how far would and could the battery push their horseflesh?