A History of Warfare.

• Author: Lancaster, John

Don't be put off by the title; A History of Warfare is no dust-gathering desk reference. John Keegan has written a lively and comprehensive account of warmaking that succeeds on the strength of its provocative theme: Namely, Clausewitz was wrong.

Karl von Clausewitz was the 19th century Prussian general and military theorist who asserted that "war is a continuation of policy by other means." Politicians and generals have been invoking his convenient definition ever since, most recently during the Persian Gulf War. But Keegan, a British military historian and newspaperman, finds Clausewitz's thought "incomplete." War, he contends, is rooted in all kinds of motivations that have nothing to do with policy as it is conventionally understood in Washington or London. Alexander the Great, he writes, was driven to expand his empire by "vainglorious impulse." Others fought for gold, land, or simply for the hen of it. In the latter category, Keegan offers the example of Mongol conqueror Genghis Khan, who is reported to have defined "life's sweetest pleasure" as follows: "Man's greatest good fortune is to chase and defeat his enemy, seize his total possessions, leave his married women weeving and wailing, ride his gelding and [use] the bodies of his women as a nightshirt and support."

In some respects, Keegan's theme is not a revelation. One need only scan the latest newspaper stories from the former Yugoslavia to know that wars do not always have a rational basis. The most useful lesson of this book is that culture, not policy, is the determinant of how and why men fight. How else to explain the reaction of Japan's Samurai warriors to the introduction of firearms in the 16th century? Rather than embrace this technological advance, the Samurai saw it as a threat to the ritualistic swordplay that defined their profession. So they confiscated every gunpowder weapon in the country, a rare achievement in national disarmament that endured for 250 years.

Keegan gallops through history at the speed of a pillaging Cossack. In less than 400 pages, he takes us from the first spear-thrusting Neanderthal through the age of mutual assured destruction. There are sections on, among other things, the biological roots of aggression, "logistics and supply," and the geographic limits to warmaking.

A lesser writer might have produced an encyclopedia, but Keegan spices his narrative with enough vivid detail to keep things moving. Consider, for example, his description of...