From the eighth century through the Middle Ages feudalism determined the nature of European warfare. "Medieval Warfare" begins in the time of Charlemagne, who maintained a military system of freemen and of vassals bound to him in service for lands granted in fief. These pages are crowded with recreations of famous events like the Battle of Hastings and movements like the Crusades; with the brightest flowers of knighthood, and with the mercenary grandeur of Byzantium.

Hans Delbruck shows how feudal military organization varied in different countries and why the knightly forces could not hold up against the barbarous Normans. He studies military developments in the kingdoms that rose with the collapse of the Carolingian Empire, as well as the trend toward mercenary armies. When the Swiss peasants, forming the first true infantry, defeated the Burgundian knights in the fourteenth century, the era of modern warfare had begun.

Moral decadence did not contribute to the fall of the Roman Empire, but political instability that was most strongly reflected in a weakened army did, writes Hans Delbruck in volume 2 of "History of the Art of War." The rise of sectionalism and the constant overthrowing of emperors left the empire without a secure superior authority demanding the loyalty of the legions and without the money to support them. Delbruck's celebrated work traces the collapse of the Roman military system and its replacement with barbarian mercenaries by the fourth century, following the invasions by the Germanic peoples.

"The Barbarian Invasions" opens with a discussion of the military organization of the early German tribes, compares it with that of the early Roman legions, and goes on to show how tactics and strategies changed after entire peoples such as the Goths, Vandals, and Burgundians migrated to Roman soil and formed an uneasy alliance with the Romans. It ends with an examination of the decline of the Germanic-Romanic military system in the Middle Ages and the rise of the feudal system.

This Bison Book edition marks the first appearance in paperback of the English translation of volume 2 by Walter J. Renfroe Jr.

Hans Delbruck's four-volume "History of the Art of War" is recognized throughout the world as the definitive work on the subject. Appearing in an English-language paperback edition for the first time, volume 1 analyzes in vivid detail the military tactics and strategies used by the great warriors of antiquity. Delbruck disputes some points in classical history and separates fact from legend in his objective reconstruction of celebrated battles stretching from the Persian Wars to the Peloponnesian War, Alexander's campaign to conquer Asia, the Second Punic War and Hannibal's crossing of the Alps, and the triumph of the Roman legions and Julius Caesar. Walter J. Renfroe Jr. based his much-praised English translation on the third (1920) edition of volume 1.

By the fifteenth century the Swiss method of warfare, in which disciplined foot soldiers fought in tightly formed units, was being imitated. The Germans and Spanish took notice when in 1479 Archduke Maximilian and his victorious Flemish infantrymen used their long pikes to prevent the mounted French knights from charging. The era of modern warmaking was at hand.

In this last volume of his classic history of the art of war, Hans Delbruck considers new developments: the use of gunpowder, the invention of firearms, and the employment of noisy large cannon that shot stone and, later, iron balls. After reviewing the establishment of a European infantry, Delbruck discusses the transformation of loose confederations of knights into cavalry (well developed by the last Huguenot wars), the organization of fighting mercenaries (followed by wives and prostitutes), and the changing of mercenary bands into standing armies.

"The Dawn of Modern Warfare" is colored by larger-than-life personalities: Niccolo Machiavelli, the theoretician of the new art of war; Maurice of Orange, renovator of the art of drill and father of military discipline; Gustavus Adolphus of Sweden, perfecter of infantry tactics; Oliver Cromwell of England, reorganizer of a citizen militia into a professional army; and Frederick the Great and Napoleon Bonaparte, military strategists par excellence.