Viewed over a period of several hundred years there is no doubt that black powder radically changed the course of human history. These changes are often acknowledged by referring to the “gunpowder revolution.” While understandable as a statement of the importance of black powder to military history, this phrase is unfortunate in that it suggests the impact of black powder weapons was sudden. This was not the case. There was a “military revolution” that came about in part because of black powder weapons, but this occurred two and a half centuries after black powder was introduced into Europe, and the contribution of black powder to the revolution was patchy. It is argued that pre-gunpowder weapons were limited in design by the strength of the weapon user, whereas the design of gunpowder weapons was free of such considerations so that firearms could be designed according to tactical needs. This is why, the argument goes, firearms generated the military revolution. Viewed long term, this statement is true, but a participant of the revolution could be forgiven for not even noticing that it was happening. Popular understanding of history often overlooks the odd stop-start contribution of firearms to the revolution.
First, some bare facts about the military revolution. Over a period of a few decades in the second half of the sixteenth century, warfare in Europe changed significantly. Armies grew in size and became more professional. Battle casualties increased (i.e., the number of casualties, as a fraction of troops involved, increased). Warfare had more of an impact on societies. These are the facts; what is in doubt is the degree to which these changes were brought about by firearms. We have seen that, during their first two centuries, firearms evolved in many directions as weapons designers sought the best ways of exploiting the new black powder. However, the military revolution rook place at a time when firearms evolution was slowing down, after the development of corned black powder and of the wheel-lock pistol. So what role did firearms play?
The first major impact of black powder weapons was in siege warfare. Early cannon made short work of medieval castles, which were designed to resist trebuchet stones, not the relatively high-speed stone balls fired from large guns. Sieges became shorter—a significant development. Then new fortifications, designed especially to withstand cannon fire, were built to replace castles. This restored the status quo; sieges became as time-consuming as they had been formerly. So cannon were not responsible for the military revolution.
Increased casualty rates were probably due to firearms. The damage done by early ballistic weapons was not selective or controllable. A bombardier or musketeer could not choose to merely wound, not kill, an enemy and then take him prisoner for ransom in the medieval fashion—he pointed his weapon in the general direction of the enemy and fired. The large increase in casualties was particularly severe among the rich and influential leaders, a fact that was commented upon at the time. These people would formerly have been disarmed and ransomed, but a cannonball does not stop to inquire about disposable income.
The increasing size of armies was in part due to nonmilitary reasons. At the beginning of our period the general population was rebounding from the effects of the Great Plague. Later, economic hard times drew peasantry into military service in large numbers. On the military side, the growth of armies was also an indirect consequence of the effectiveness of pikemen against cavalry; dense pike formations were introduced to many European armies during this period. The effectiveness of this tactic, combined with the immobility of gunpowder weapons, led to defensive warfare. Defenders would usually win a battle, so battles were avoided. Consequently campaigns were decided by territorial occupation, which required the service of lots of soldiers. Here we find reasons for the greater impact of warfare on society: the tendency toward occupation was felt by the wider population. The increased tax burden and the logistics of supplying larger armies was felt by all.
One of the few clear-cut examples of firearms’ influencing the military revolution is supplied by wheel-lock pistols. When these pistols became inexpensive enough to be widely distributed, they led, as we have seen, to the demise of heavy cavalry. This demise led to the disbandment of pike formations, which in turn had consequences for the dominance of defense.
THE DEVELOPMENT OF UNDERSTANDING
A lot of the improvements in black powder weapons that I have summarized in the preceding sections were motivated by military necessity. The consequences for a country of losing a war were disastrous for national prestige and well-being. In an age when European wars were frequent, there was great incentive for improving military technology. Much of this improvement was empirical—by trial and error—but in the eighteenth century the understanding of military technology began to be placed upon a more scientific footing. (Trial and error can be a perfectly valid scientific approach: it combines experimental variation with intelligent interpretation of results.)
In 1742 a British mathematician and military engineer named Benjamin Robins published a book called New Principles of Gunnery. In it, he showed the results of experiments that he had conducted on numerous firearms to establish, for example, the relationships between gun caliber, barrel length, powder charge, and projectile muzzle speed. These measurements were made with a ballistic pendulum, a device that he invented to estimate muzzle speed. The use of ballistic pendulums spread far and wide, and the original design lasted for more than a century before being superseded by an electronic measuring device, the chronograph, which operated on different principles. The ballistic pendulum, and Robins’ scientific approach, have led to his being widely acclaimed as the father of modern ballistics. Robins by no means solved all of the many and varied problems of internal ballistics, but he showed us how to proceed. Leon-hard Euler, the famous Swiss mathematician of the late eighteenth century, critiqued and expanded upon Robins’ work. His mathematical approach did much to transform ballistics into the mathematical science that it is today. Between them, the two men turned a trial-and-error field into a scientific discipline.
There were also earlier scientific investigators. These innovators included Charles V, sixteenth-century Holy Roman Emperor, who tested the range of a long culverin. The original length was 58 calibers, but this was successively decreased to 50, then 44, then 43 calibers, and it was found that the range increased with each reduction. At the time, this finding must have caused some confusion because the general belief in those early days was that the range of an artillery piece increased with increasing barrel length (assuming that the same weight and quality of charge was used in all cases). Consequently, many culverins were of enormous length. One reason for the belief was that it seemed to be true for small arms that range or muzzle speed increased with barrel length.
In the nineteenth century more precise experiments showed that there was an optimum bore length, in calibers; for barrels longer or shorter than this optimum the muzzle speed (and therefore the range) was reduced. Further, this length depended upon the charge. Also, the optimum length for a barrel (measured in calibers) was found to be greater for small arms, which fired lead shot, than for cannon, which fired solid iron balls. The optimum length for cannon was greater than the optimum lengths for howitzers and mortars, which fired hollow shot. So it seemed that optimum barrel length increased with projectile weight or density and depended upon the power of the charge.
Black powder is a mixture that deflagrates upon ignition; the best form for this mixture depends upon the gun and was found by trial and error over centuries. Similarly, the best design for guns was found by empirical tinkering—trial and error—particularly during the first two centuries these weapons were in use. A simple mathematical model of internal ballistics can explain many of the features observed in real firearms, such as the dependence of muzzle speed upon barrel length.