86 Chapter Threeexplosion to accelerate the projectile while it traveled the length of
the barrel. Such a design produced far higher velocities than had been
attainable before.
Higher velocities, in turn, induced gunmakers to try for bigger and
bigger calibers on the theory that a larger projectile would exercise
decisive shattering force on enemy fortifications. Bigger guns carrying
heavier projectiles and larger charges of powder had to be made
stronger. The earliest giant guns were fabricated by welding bars of
wrought iron together; but such “bombards” were liable to burst. A
more satisfactory solution was to employ metal-casting techniques
which European bell makers had already developed to a high degree
of perfection. Guns cast as a single piece of bronze or brass proved far
more reliable than any built-up design, all of which were, accordingly,
abandoned.
By 1450, therefore, supplies of copper and tin to make bronze and
of copper and zinc to make brass became critically important for
Europe’s rulers. When the new guns spread to Asia, a second bronze
age set in. It lasted for about a century until technicians imported into
England from the Continent discovered in 1543 how to cast satisfac
tory iron cannon. They thereby cheapened big guns to about a twelfth
of their former cost, just as the iron-age blacksmiths had cheapened
swords and helmets in the twelfth century B.C.^16
Strictly speaking, therefore, the second bronze age lasted less than a
century (1453–1543). But English ironmasters could not supply every
ruler of Europe; and even after the Swedes and Dutch developed an
international trade in iron guns in the 1620s, bronze and brass cannon
continued to be preferred. Thus, for example, it was only in the
1660s, when Colbert set out to build a navy and needed thousands of
guns for his ships and shore installations, that the French went over to
- Theodore A. Wertime, The Coming of the Age of Steel (Leiden, 1961), pp. 67–69;
H. R. Schubert, History of the British Iron and Steel Industry from c. 450 B.C. to A.D.
1775 (London, 1957), pp. 164 ff. On the Continent, cast iron cannon actually dated
back to the mid-fifteenth century but were often defective, so the cheapness of the metal
was counteracted by the frequency of failure. England retained an effective monopoly
of serviceable cast iron cannon for half a century, largely because minute chemical trace
elements in the ore used by the Sussex ironmasters made the metal less likely to
develop flaws as it cooled.
Military demand for cannon slacked off after 1604 when England made peace with
Spain (and the Dutch soon followed suit). Growing fuel shortages deepened the eco
nomic depression that then set in in Sussex; and two decades later Sweden began casting
iron guns of high quality, thanks to the import of Walloon techniques of blast furnace
construction and metal casting. Thereafter the Swedes dominated the international
market in iron cannon until late in the eighteenth century. Cf. Eli Heckscher, “Un grand
chapitre de l’histoire de fer: le monopole suédois f Annales d’histoire économique et sociale
4 (1932): 127–39.