The French soldiers at the Battle of Agincourt were so exhausted by the time that they entered battle that they could barely have fought, according to new research reported in the Guardian. A professor of biomechanics asked staff from the Royal Armouries Museum to walk and run in replica armour from the 15th century, based on a variety of designs, and took measurements of oxygen use, which enables estimates of energy consumption. The Guardian website has a video of how they did it.

Apparently running in a typical suit of armour uses 2 times as much energy as running in normal clothes, because the armour weighs up to 30kg; but worse than that, running in a backpack carrying 30kg of weight uses only 1.7 times as much energy. This is because the armour distributes some of that 30kg onto the limbs, which move more than the back during ordinary movement. Additionally, armour constricts breathing. The news report also points out that in Agincourt the French had to slog through mud, which would further add to their energy load. Interestingly, armour is comparatively more efficient when running (1.9 times the energy load) than walking (2.3 times).

I’ve always been suspicious of mediaeval re-enactors oft-repeated claims that plate armour is easy to move in and not that exhausting. I suspect this comes from their limited experience of battle. I’m guessing that most mediaeval re-enactment battles cut straight to the chase, and ignore the lived experience of 15th century soldiers. Most battles probably consisted of many hours of standing and walking, and obviously we don’t do things like mediaeval re-enactment in order to reproduce the tedium of ancient warfare (or the cholera and dysentery, for that matter). So if you cut out the long, arduous process of getting to and from the battle, waiting fororders, etc. the armour probably doesn’t seem so bad. But if you think about moving around for hours in it, and the battle itself just a short part in the middle, you can see that the energy expense of just walking would be a terrific burden on the use of armour. When we think about adventurers in caves and dungeons, slogging around for hours in their full plate, it makes sense that it should put an inordinate penalty on their combat actions to represent this. Warhammer 3 reproduces this nicely with punitive encumbrance rules that quickly punish characters with fatigue penalties; I don’t think D&D was ever so good at this (largely because no one ever bothered with the encumbrance rules, I guess). Of course Rolemaster does it with complex movement manoeuvre penalties, which would be really good if they were combined with fatigue (which I don’t recall RM using).

I think the Guardian has probably over-egged the pudding on this one though, so here’s a few additional thoughts:

  • The study subjects weren’t fit: Some workers at the Royal Armouries are probably re-enactment types[1], and might be used to armour, but at a guess most of them weren’t that fit or trained for running in armour. My guess is that, just as longbowmen trained to use the bow, mediaeval soldiers trained for their armour, though this guess could itself be over-optimistic (“training” is actually a pretty modern concept). So it could be that the relative burden of armour compared to no armour is reduced in mediaeval soldiers compared to modern archivists, since fitness training tends to adapt the body to specific activities
  • The study subjects were modern: and thus almost certainly physically healthier than a mediaeval soldier, with better diet and less childhood illnesses to reduce fitness. However, they were likely also bigger, and bigger people (I think) use energy less efficiently. But one should never underestimate the importance of good modern diet, housing and healthcare (as well as childhood fitness training at school) in improving the fitness of modern people over their ancestors. So it could be that armour was even more exhausting for the mediaeval knight
  • Study bias due to armour type: Wikipedia tells me that actually most soldiers didn’t use the type of armour depicted in the video on the Guardian site, and were more likely to wear weaker wrought iron or composite armour types, that are probably also easier to move in (though wrought iron full plate could be awful, I would guess!) It also tells us that the elite knights in the vanguard at Agincourt[2] were relatively unharmed by the longbows. Still, they would then have to engage in melee combat against lightly-armoured and mobile foes while exhausted. So the best tactic for these guys would be to ensure they were surrounded by less heavily-armoured allies while they regained their breath; unfortunately, the longbowmen would have reduced the numbers of those less armoured mooks quite hideously (the stats and description of the bows at that wikipedia entry suggest that for the lighter-armoured French soldiers Agincourt would have been truly terrifying). In any case, the army fielded at Agincourt would not have looked much like the army being tested in the linked study
  • The longbow was actually not that effective: Wikipedia also tells us that, although they had a few successful battles, the French quickly got the measure of the longbowman as a weapon of war, and in some battles either defeated them or routed them. This is probably because tactics based on the longbow depend on this phenomenon of exhaustion – you thin out the lightly-armoured troops in the charge, and by the time the knights reach you they’re too buggered to fight. But I guess this depends on either a numerically superior force or having very good positioning to force a long charge (as happened at Agincourt, with mud). This goes to show that tactics are ultimately more important than most single weapons or devices. Also, I guess that although the longbowman appears, superficially, as an appealing strategic investment (lightly armoured, so cheap to equip, and manpower was something every mediaeval country had an excess of), he was probably actually a type of elite professional troop that was highly expensive to develop (15 years on that bow!), and you only need to beat them in battle once or twice to have essentially destroyed a once-in-a-generation investment. So maybe as a military tactic the longbow was as much of a dead end as the knight. The pikeman, on the other hand…

It’s nice to see science attempting to answer some of these questions about how the ancient world waged war or achieved some of its more impressive peace-time achievements (like the science of longitude, cathedrals, etc.) Some of what we think of now as quite barbaric or backward practices, or don’t esteem because they’re trivial in the modern world (like church-building) actually required prodigious talent and willpower (like any kind of mediaeval warfare) or skill, and it’s good to appreciate that.

fn1: If you’re from the Museum and you’re reading this, please don’t sue me for this slur

fn2: Ah, the days when the people who chose to go to war actually had to lead the charge! I bet if that were expected of your average modern politician, we would have much much lower “defence” budgets that were actually for defence.