Photo: A volunteer in replica armor has his oxygen use measured while walking on a treadmill. Courtesy of Graham Askew, University of Leeds.
One of the greatest English military victories, the Anglo-French Battle of Agincourt, could have turned out differently if the French had worn lighter armor, a new study suggests.
Fought on Oct. 25, 1415, during the Hundred Years' War, the battle was a sort of medieval equivalent of David and Goliath, with the French knights significantly outnumbering (possibly as much as six to one) Henry V's soldiers.
Historians have attributed the unexpected English victory to a number of causes, including the English's army use of the longbow.
But according a study which investigated the limitations of wearing a medieval armor, the French lost the battle before the fight had even started.
"The heavily armored French knights advanced towards the English men-at-arms across terrain made extremely muddy from recent ploughing, over night rain and an earlier French cavarly charge," a team of researchers from the Universities of Leeds, Milan and Auckland wrote in the Proceedings of the Royal Society B journal.
Simply put, the French army was knocked out by fatigue.
"By the time they got to the enemy they would have been exhausted and easily killed," said lead researcher Graham Askew from the University of Leeds Faculty of Biological Sciences.
Askew and colleagues monitored oxygen consumption and energy expenditure of four historical fight interpreters from the Royal Armouries Museum in Leeds, United Kingdom as they walked and ran on treadmills in full armour.
The battle suits were exact replicas of armour made in the 15th century and featured English 1470-1480, Milanese mid-to-late 15th century and German gothic style late 15th century designs.
The armor was principally constructed from interlocking steel plates, which covered the soldiers from head to toe.
It emerged that wearing these bulky armors, which weighed between 30 and 50 kg, (66-110 lbs), doubled the amount of energy required to walk or run.
Indeed, the interpreters expended up to 2.3 times as much energy while walking and 1.9 times as much energy while running compared with wearing no armor.
"We found that carrying this kind of load spread across the body requires a lot more energy than carrying the same weight in a backpack," said Askew.
"This is because, in a suit of armour, the limbs are loaded with weight, which means it takes more effort to swing them with each stride. If you're wearing a backpack, the weight is all in one place and swinging the limbs is easier," he added.
In addition, the armour had a clear impact on the soldier's breathing. Examination of the interpreters' breathing patterns showed that the armored subjects took a greater number of shallower breaths when they were exerting themselves.
"The geometrical constraint of the armor around the chest makes it impossible to take a deep breath," co-author Federico Formenti, from the University of Auckland, told Discovery News.
"You feel breathless as soon as you move around in medieval armour, and this would likely limit soldiers' ability to fight," Formenti said.
According to the researchers, the new biomechanical and physiological results offer the potential to more accurately interpret the tactics employed during European medieval battles.
Heavy armor may have also contributed to the French defeat at the Battle of Crécy in 1346. On that occasion, an English army of 9,000 to 15,000 men commanded by Edward III of England defeated Philip VI of France's force of 35,000 to 100,000 soldiers.
Similarly, the French knights lost after an exhausting march lasting several days.
"Together with numbers and condition of soldiers, equipment availability, battle strategy and terrain, the high energetic cost of movement in armor could have contributed to the outcome of medieval battles," the researchers concluded.