The Business of War in Europe, 1000–1600^71wide market. Bills of exchange facilitated payment across long dis
tances. Credit became a lubricant of commerce and also of specialized,
large-scale artisan production. A more complexly differentiated, po
tentially richer, yet correspondingly vulnerable economy began to
control more human effort than in earlier centuries. Cities of north
Italy and a secondary cluster of towns in the Low Countries remained
the organizing centers of the whole system of exchanges.
Geographically, waters which had previously been effectively sepa
rated from each other became for the first time parts of a single sea
room. The Black Sea to the east and the North Sea to the west fell
within the extended scope of Italian-based shipping. Previously, the
risks of seafaring in winter and on stormy seas had combined with
political barriers at the Straits of Gibraltar and at the Dardanelles and
Bosphorus to isolate these bodies of water from each other. Similarly,
German shipping based in the Hansa ports linked the Baltic with the
North Sea coast, where exchanges with the Italian-dominated seaways
of the south occurred. The Baltic lands, indeed, entered upon a fron
tier boom in the fourteenth century at a time when other parts of
Europe were troubled first by overpopulation and then by plague and
social strife. Salt imported from the south enabled Baltic populations
to preserve herring and cabbage through the winter. This assured a
vastly improved diet, and an improved diet soon made manpower
available for cutting timber and raising grain for export to the food-
and-fuel-deficient Low Countries and adjacent regions.
Another economically important advance took place in the field of
hard rock mining. In the eleventh century, German miners of the
Harz mountains began to develop techniques for penetrating solid
rock to considerable depths. Fracturing the rock and removing it was
only part of the problem. Ventilation and drainage were no less neces
sary, not to mention the skills required for finding ore, and refining it
when found. As these techniques developed, each reinforcing and
expanding the scope of the others, mining spread to new regions,
moving from the Harz mountains eastward to the Erzgebirge in
Bohemia during the thirteenth century and then to Transylvania and
Bosnia in the course of the fourteenth and fifteenth centuries. Silver
was the principal metal the German miners sought; but copper, tin,
coal, and iron could also be mined more cheaply and in greater abun
dance by using techniques initially developed by silver miners.^6
- No satisfactory account of the techniques of European mining before the sixteenth
century seems to exist. Maurice Lombard, Les métaux dans l’ancien monde du Ve au XIe
siècle (Paris, 1974) breaks off just when European mining surged ahead. T. A. Richard,