A History of Warfare.

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 chariot warfare around the middle of the second millennium B.C. "Circling at a distance of 100 to 200 yards from the herds of unarmored foot soldiers, a chariot crew - one to drive, one to shoot [arrows] - might have transfixed six men a minute. Ten minutes' work by ten chariots would cause 500 casualties or more, a Battle of the Somme-like toll among the small armies of the period."

For all the ancient history he covers, Keegan's main focus is closer to home. His animating premise is that Clausewitz was not only wrong but dangerous. In arguing that war and politics are part of the same continuum, Keegan writes, Clausewitz gave ideological cover to the reckless militarization of 19th century European society. Conscription armies became the norm, military service a male rite of passage. These trends combined with technological advances such as machine guns and rapid-fire artillery to produce the unparalleled slaughter of World War I. Clausewitz also gets much of the blame for World War II: "Revolutionary weapons, the warrior ethos, and the Clausewitzian philosophy of integrating military and political ends were to ensure that, under Hitler's hand, warmaking in Europe between 1939 and 1945 achieved a level of totality of which no previous leader... had ever dreamed." It was only the advent of nuclear weapons, Keegan writes, that "exposed the hollowness of the Clausewitzian analysis once and for all. How could war be an extension of politics, when the object of rational politics is to further the well-being of political entities?"

Keegan ends his book on a faint note of optimism. "All we need to accept is that, over the course of 4,000 years of experiment and repetition, warmaking has become a habit," he writes. Habits that are learned can also be unlearned: Keegan finds some evidence that the major powers may be starting to do so. Exhibit A is the growing preoccupation with multi-lateral peace-keeping operations of the sort now being contemplated for Bosnia-Herzegovina. Interestingly, Keegan cites as the most significant bright spot of recent years not nuclear disarmament or the Russian rejection of Marxism but the Soviet Union's decision, "in the last months of existence," to back the multi-national coalition that drove Iraq out of Kuwait in 1991.

Some readers will find Keegan's subject too broad to fit comfortably between two covers. My own view, however, is that he has largely succeeded in knitting together history's disparate strands. This is a valuable book for anyone trying to make sense of an increasingly disordered world - one that Clausewitz would never have understood.