Today, the crossbow -- and the problem of competing
technologies. The University of Houston's College
of Engineering presents this series about the
machines that make our civilization run, and the
people whose ingenuity created them.
The military crossbow showed
up in the Battle of Hastings. It lasted about 300
years. Then it gave way to firearms.
In one sense crossbows were much older than
Hastings. After all, they were just regular bows
mounted on a grooved stock and fitted with a
trigger. And the Roman siege catapult was really a
large crossbow. But we didn't reduce that siege
engine to a hand-held replacement for the bow and
arrow until the Middle Ages.
Once we did, the crossbow evolved quickly. We
strengthened the bow. Then we made it of spring
steel. First we used levers -- then cranks -- to
pull bow strings with forces of over half a ton. We
soon had a terrible weapon with a range of over 300
yards.
In 1139, a Church council declared crossbows unfit
for Christian use -- except against Infidels. In
the next decades other councils repeated the ban.
So Crusaders carried crossbows to the Holy Land,
and they kept on developing the technology.
The crossbow became a regular part of military
tactics. When the ban was inconvenient, kings
forgot it. I suppose any enemy became an Infidel on
the battlefield.
The crossbow's great test came in 1346 at the
Battle of Crécy in Northern France. Edward
III's English army met the French. The French had
20,000 mercenary crossbowmen and some of their own
cavalry. Edward's troops carried English longbows.
The weather and terrain ran against the French. To
load a crossbow you put the bow on the ground and
crank the bow-string back. It takes firm ground and
time. The ground at Crécy that day was mud.
Even under good conditions, a skillful English
archer with a manual longbow could loose 5 or 6
arrows while a crossbowman was still turning his
crank. This day, the English riddled the
crossbowmen 'til they fled into their own cavalry.
A newer weapon also made its debut at Crécy.
It was probably the first major battle that
involved firearms. Gunpowder wasn't a major player
at Crécy. It was an omen.
A century later, the crossbow gave way to the gun.
And we read a parable of technological progress at
Crécy. The hottest technology -- the
crossbow -- took the field with two competitors.
The older of the two, the longbow, did better in an
open field under bad conditions. The younger, the
gun, was still ineffective at Crécy. But it
wouldn't stay so for long! By 1585, the surgeon
Ambroise Paré, sick of gunshot wounds,
cried,
. . . we . . . rightfully curse the author of so
pernicious an engine; [and] praise those to the
skies, who endeavor by words and pious exhortations
to [dissuade] kings from its use.
Well, no one ever dissuaded a king from
using new weapons. And we never have done well at
predicting how new weapons will fare.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
