Over the next several decades, the world is destined to experience a revolution in the character of warfare. Indeed, the way in which the United States and its allies won a quick and overwhelming victory in the Gulf War suggests to many that we are already in the early stages of such a military revolution. But if so, there is much more to come.

As it progresses, this revolution will have profound consequences for global and regional military balances, and thus for U.S. defense planning. In the past, military revolutions have induced major changes in both the nature of the peacetime competition between states and their military organizations, as well as in the ways wars are deterred, fought, and resolved. By changing radically the nature of the military competition in peace and war, military revolutions have changed the "rules of the game." In so doing, they have often dramatically devalued formerly dominant elements of military power, including weaponry, weapons platforms, and doctrines. Military organizations that did not adapt in a rapidly changing, highly competitive environment have declined, often quite quickly.

What is a military revolution? It is what occurs when the application of new technologies into a significant number of military systems combines with innovative operational concepts and organizational adaptation in a way that fundamentally alters the character and conduct of conflict. It does so by producing a dramatic increase--often an order of magnitude or greater--in the combat potential and military effectiveness of armed forces.

Military revolutions comprise four elements: technological change, systems development, operational innovation, and organizational adaptation. Each of these elements is in itself a necessary, but not a sufficient, condition for realizing the large gains in military effectiveness that characterize military revolutions. In particular, while advances in technology typically underwrite a military revolution, they alone do not constitute the revolution. The phenomenon is much broader in scope and consequence than technological innovation, however dramatic.

The transition from the Cold War period of warfare to a new military era that is now anticipated may take several decades--or it may arrive within the next ten or fifteen years. There is no common transition period from one military regime to another: the naval transition from wood and sail to the all big-gun dreadnoughts with their steel hulls and turbine engines took roughly half a century; the emergence of nuclear weapons, ballistic missile delivery systems, and associated doctrine and organizational structures took roughly fifteen years. The rate of transition is typically a function not only of the four elements noted above, but of the level of competition among the international system's major players, and the strategies the competitors choose to pursue in exploiting the potential of the emerging military revolution.

It may be argued that with recent transition periods of ten to twenty years, we are discussing a continuous military evolution rather than a revolution. But what is revolutionary is not the speed with which the entire shift from one military regime to another occurs, but rather the recognition, over some relatively brief period, that the character of conflict has changed dramatically, requiring equally dramatic--if not radical--changes in military doctrine and organizations. Just as water changes to ice only when the falling temperature reaches 32 degrees Fahrenheit, at some critical point the cumulative effects of technological advances and military innovation will invalidate former conceptual frameworks and demand a fundamental change in the accepted definitions and measurement of military effectiveness. When this occurs, military organizations will either move to adapt rapidly or find themselves at a severe competitive disadvantage.

From Cavalry to Nuclear Weapons

There appear to have been as many as ten military revolutions since the fourteenth century. The Hundred Years' War (1337-1453) spawned two of them. The first was the so-called Infantry Revolution, which saw infantry displacing the dominant role of heavy cavalry on the battlefield. During the period leading up to this military revolution, infantry typically employed tight formations of pole-arms and crossbowmen to protect the cavalry while it formed up for a charge. During the first half of the fourteenth century, however, the infantry--in the form of Swiss pikemen and English archers--emerged as a combat arm fully capable of winning battles, as was demonstrated at the battles of Laupen (1339) and Crecy (1346). Following these engagements, major cavalry actions on the field of battle became increasingly rare.

Clifford Rogers cites several factors as responsible for the Infantry Revolution. One key factor was the development of the six-foot yew longbow, which gave archers a much enhanced ability to penetrate the armor of cavalrymen. It also gave archers both missile and range superiority over their adversaries. England, which developed a pool of yeoman archers over decades of warfare against the Scots and Welsh, established a significant competitive advantage over the formerly dominant army, that of the French, which failed to exploit the revolution until late in the fifteenth century.

But it was not the longbow alone that fueled the revolution. Once the ability of infantrymen to win battles was clearly established, tactical innovations followed. The English developed a tactical system based on integrating archers with dismounted men-at-arms. Interestingly, the dominance of infantry was given an additional boost by the fact that archers were far less expensive to equip and train than men-at-arms. Thus, Rogers points out, the tiny kingdom of Flanders, which was relatively quick in exploiting the revolution, was able to muster a larger army at Courtrai (1302) than the entire kingdom of France. Finally, the Infantry Revolution marked a sharp increase in casualties on the battlefield. Whereas formerly it had been important to capture knights for the purpose of realizing a ransom, common infantrymen neither held that value, nor did they share knightly notions of chivalry. Battles thus became more sanguine affairs.

The Infantry Revolution was succeeded by the Artillery Revolution, which dramatically altered war in the latter period of the Hundred Years' War. Although Roger Bacon's recipe for gunpowder dates back to 1267, cannons only began to appear on the European battlefield in significant numbers some sixty years later. Even then, almost a full century passed before artillery began to effect a military revolution. During this period besieged cities typically surrendered due to a lack of supplies. In the 1420s, however, a major increase occurred in the number of besieged cities surrendering as a consequence of the besiegers' artillery fire fatally degrading the cities' defenses. In the span of a few decades, gunpowder artillery displaced the centuries-old dominance of the defense in siege warfare.

Several technological improvements underwrote the Artillery Revolution. One was the lengthening of gun barrels, which permitted substantial increases in accuracy and muzzle velocity, translating into an increase in range and destructive force (and also the rate of fire). Metallurgical breakthroughs reduced the cost of iron employed in fabricating gun barrels, reducing the overall cost of cannons by about a third. Finally, the "corning" of gunpowder made artillery more powerful and cheaper to use. As one Italian observer noted, artillery could now "do in a few hours what . . . used to take days." Unlike the Infantry Revolution, the Artillery Revolution was expensive to exploit. As early as 1442 the French government was spending over twice as much on its artillery arm as on more "traditional" military equipment.

A kind of snowball effect developed. The richer states could exploit the Artillery Revolution to subdue their weaker neighbors (or internal powerful regional nobles), which in turn increased the resources available to exploit their advantage further. This phenomenon was a significant factor in the growth of centralized authority in France and Spain. Along with the changes in technologies that spawned the great improvements in artillery and changes in siege warfare, new military organizational elements, such as artillery siege trains, were formed to cement the revolution. Once this occurred, defenders could no longer rely on castles for protection. This led to further changes in military organizations and operations, as the defenders now had to abandon their fortified castles and garrison units and move the contest into the field. And, as Francesco Guicciardini wrote, "Whenever the open country was lost, the state was lost with it."

Military revolutions were not limited to land. The Revolution of Sail and Shot saw the character of conflict at sea change dramatically, as the great navies of the Western world moved from oar-driven galleys to sailing ships that could exploit the Artillery Revolution by mounting large guns. Galleys, being oar-driven, had to be relatively light, and, unlike ships propelled by sail, could not mount the heavy cannon that could shatter a ship's timbers, thus sinking enemy ships rather than merely discouraging boarding parties. Indeed, prior to the late fourteenth century, ship design had not improved significantly for two millennia, since the age of classical Greece. The French first mounted cannons on their sailing ships in 1494. But the death knell for the galley did not sound clearly until the Battle of Preveza, when Venetian galleasses won an overwhelming victory against Turkish galleys. The result was repeated at Lepanto in 1571. By 1650 the warship had been transformed from a floating garrison of soldiers to an artillery platform.