Plague, War, and Social Change in the “Long”Fourteenth Century 223imperceptible change. This is an illusion that comes
from thinking of the inventions themselves instead of
the complex process that created them, but periods cer-
tainly existed during which breakthroughs occurred at
an accelerated rate. One of these was the later Middle
Ages. Few of the changes had an immediate impact on
everyday life, but their effects on war, trade, and gov-
ernment were great.
The development of artillery and portable firearms
is a case in point. Evolution began with the invention of
gunpowder. In Europe, saltpeter was first identified in
the twelfth century. How or why it was combined with
charcoal and sulphur is unknown, but the mixture was
mentioned by Roger Bacon in 1248. A number of years
passed before it was used as a propellent, and its first
application probably was in mining. This, however, is
uncertain. Only the obstacles to its use are fully docu-
mented. Saltpeter was scarce and expensive. Years of
experimentation were needed to arrive at the proper ra-
tio of ingredients and even longer to develop grains of
the proper consistency. Mistakes were often fatal, for
black powder was not totally safe or dependable in use,
and its chemistry has only recently been understood.
Nevertheless it presented fewer problems than the
construction of the guns. Metallurgy, not powder
milling, controlled the pace of artillery development.
The first guns, which appeared around the middle
of the fourteenth century, were hand forged from
wrought-iron bars and bound with iron hoops. They
were heavy, expensive, and prone to bursting when
fired. In spite of these drawbacks, they remained domi-
nant until the middle of the fifteenth century when
they were superseded by guns cast from bronze. The
bronze used was approximately 80 percent copper and
20 percent tin. Large quantities of both metals were
therefore required, and gun production on a large scale
was prevented during the fourteenth century by the ex-
haustion of existing mines. Copper in particular was in
short supply. In 1450 a new process was introduced
that extracted copper from ores in which copper and
silver were found together. Large, previously unusable
deposits in Saxony, Hungary, and Slovakia thus could
be exploited, and copper production increased
dramatically.
The introduction of bronze cannons was further
delayed by the lack of adequate furnaces and by an in-
ability to deal with a physical property characteristic of
bronze. Copper and tin tend to segregate as they cool,
causing variations in the strength of the metal that
might cause the guns to burst when fired (see illustra-
tion 12.3). Generations of experience were needed to
solve these problems. By the 1460s they were largely
under control, and large numbers of bronze cannons
were quickly added to European armories. Within a
half-century, every existing fortress was obsolete, for
the high, relatively thin walls of medieval fortifications
could withstand no more than a few hours of battering
by the big guns. Towns and strongholds in militarily
exposed areas were forced to rebuild if they were to
survive. Between 1500 and 1530, Italian engineers de-
veloped a system of fortifcation that set the pattern forIllustration 12.3
Gun-Casting Technique (after c. 1450).The gun was cast
around a core that was lowered into the mold and centered by an
iron “cross” that was left in the casting. The pouring head at the
top ensured that the mixture of tin and copper would not segre-
gate during cooling and weaken the breach. The head was sawed
off after the casting process was complete.