Sunday, March 24, 2013

Real Overland Movement

A friend of mine has been working on a series or articles on the role of beasts of burden in war. First up the camel, and now the mule. They are short and fascinating pieces, not least of all because of the game ideas they can churn up. Take, for example, this excellent chart that has been reproduced from a 19th century British military handbook.

Animal Speed (Miles per Hour)
Pack Load (Pounds)
Draught Load (Pounds)
Work Day (Distance in Miles)
50-100 by sleigh

The original source for these figures is The Soldier's Pocket-Book for Field Service by Field Marshal Garnet Wolseley (a Modern Major General with an amazing bio of his own).

One thing that strikes me about this table is how different the numbers are from those given for overland movement in gaming. Take the d20 SRD for example. The mule numbers match up pretty well, but the gaming horses are way faster than the real horses, covering 40 or 48 miles in a day. Of course, Wolseley's numbers have to consider the movement of these animals as part of a large force, but I do wonder how various gaming systems came up with their overland movement rates. There's much more to be explored in this regard.

In general, gaming needs more rules for reindeer. (New York Public Library)


  1. there's a simple reason: animals travel at vastly different speeds in different conditions.

    A fresh (watered, fed, unused until that day) horse with little baggage can travel like 100 miles in a day.

    A small unit of PCs is going to move faster than a military column which always must move at the speed of its slowest members.


  2. If you take the work day and divide it by the speed, you get an estimate of how many hours Woolsey thinks that particular mode of transportation can be used in a day. For example, if he thinks that humans can cover around 8 miles in a day, and that they travel at 2.5 mph, that implies he thinks that soldiers are only willing to spend about 3 hours marching.

    Granted, those are some pretty heavy packs they're carrying! But I'd still hope that monster-slaying heroes could manage to walk for more than three hours out of a day.

    Anyway, Woolsey's numbers for horses assume that they can only travel for four hours a day, based on 16 miles at 4 mph. The Wikipedia page for "Endurance Riding" suggests that an optimally trained Arabian can cover 100 miles in about 10-12 hours (with a saddle rider weighing over 200 lbs). This is a huge discrepancy, even allowing for somewhat heavier packs in the army, suggesting that horse quality is a major contribution to differential. An army with cheaper, low-quality horses can't even cover a fifth of the daily distance of a world-champion trail horse!

  3. I think the key take-away is that lots of different factors can encumber an animal's performance. For a military riding in large numbers, these factors will be many. Adventuring PCs will have fewer, but often, the movement is just taken for granted. It strikes me that there are a lot of ways to create interesting variations on this, either in making a fresh rule set or for messing with your own PCs.

    One of the articles I've linked to, for example, notes how important it was to have well-trained mule drivers. There can be bonuses for having the right kind of animal handling skill, or penalties for not.

  4. I think a lot of it has to do with the general slowness at which large forces move. As Edward points out, the chart assumes only 3-4 hours of useful travel per day. With rest breaks and the difficulties of starting and stopping a large force -- the difficulties of doing ANYTHING, from breaking out a snack to finding a tree to water, when you're multiplying it times 10,000 -- you're not going to get a full day on the road out of your army. But you well might out of your 6-person adventuring party.

    Still, Woolsey's numbers strike me as a bit low -- civil war soldiers are typically credited at 10-20 miles/day, for example, which is rather substantially above 4-8. On the other hand, civil war soldiers were usually marching on decent roads in forgiving terrain while the British Army, generally, wasn't. Terrain matters. Roads matter. Organization and discipline matter. The size of your force matters -- 6 travel faster than 6,000, and 6,000 travel faster than 60,000. Weather, heat, mud.

    I don't think the endurance riding comparison is a good one, as that's like comparing the human soldiers to marathon times. Horse quality does matter, but the bigger differences are just what they are for people -- the logistics of moving large groups and the quality of the ground they're moving over.

    Really, I think the primary takeaway here is just that the movement rate of a small group and the movement rate of an army aren't really comparable. If you were trying to write a rule for it, I suppose you'd set a base movement rate and then come up with some formula to reduce it by the number of people in your group.