By John Keegan. Knopf. 254 pp. $24.95

Amid the painful news from Iraq, it's comforting to cast one's mind back long, long ago . . . a year ago, to be precise, when Anglo-American arms appeared triumphant, the Baathists were defeated, and a bright new day was dawning for a long-oppressed people.

John Keegan takes us back to the not-so-long-ago world where it could reasonably be said -- as he says on page one -- that "The Iraq War of 2003 was exceptional in both beginning well for the Anglo-American force that waged it and ending victoriously." True enough, if one defines the war in narrow terms, as the 21-day period between March 20 and April 9, 2003, when coalition forces raced from Kuwait to Baghdad. Unfortunately, that seems to be the way that U.S. military planners defined their task, giving insufficient thought to what would happen after Saddam Hussein fell. We still don't know the answer to that question, and, while it's possible that everything will work out fine, it seems less probable today than it was when the world watched Saddam's statue fall in Firdaus Square.

Keegan provides a vivid account of how we got here, emphasizing the coalition's successes, though he touches upon some failures in a concluding chapter. Unlike many other authors of instant histories of the Iraq War, Keegan was not embedded with the allied forces. What his account lacks in ground-level details, it more than makes up for with a panoramic perspective befitting the best-known (and perhaps the best, period) military historian in the world.

He does not get to the actual Iraq War until more than halfway through The Iraq War. The first part of the book is devoted to a summary of prewar Iraqi history -- a task that no one has undertaken more elegantly or intelligently. He begins with ancient Mesopotamia and marches briskly through Ottoman rule, the British creation of Iraq from three Ottoman provinces in the 1920s, Iraq's peaceful days as a constitutional monarchy, the 1958 military coup that inaugurated a time of troubles, the rise of Saddam Hussein in the 1970s, his wars of aggression against Iran and Kuwait and his comeuppance in the 1991 Gulf War. Keegan is unsparing in his depiction of the "violent and self-centered" dictator who was "a monster of cruelty and aggression." He then spends a chapter chronicling "The Crisis of 2002-03" which preceded Saddam's final downfall, in which the author's sympathies clearly lie with Tony Blair and George W. Bush, not with Jacques Chirac and other opponents of the war.

All this is by way of appetizer. The main course is three chapters chronicling the three weeks of major combat. Keegan provides a fluent narrative, informed by a lengthy interview he conducted afterward with the coalition commander, Gen. Tommy Franks. The blow-by-blow account of how the 3rd Infantry Division and the 1st Marine Expeditionary Force blitzkrieged their way to Baghdad does not contain much that is new for those who closely followed press coverage of the war. The chapter on "The British War," on the other hand, does contain a good deal of information that will be fresh to most American readers.

Keegan is properly laudatory of the capabilities of the U.S. armed forces, many of which, he points out, cannot be matched by their poorer British cousins. But he also stresses that the British played an integral role, contributing "almost a third of the coalition force deployed," as well as with "their long experience of pacification operations." That knowledge was put to good use by the British commander, Maj. Gen. Robin Brims, in his handling of Basra, Iraq's second-largest city. He cleverly avoided a block-by-block fight, choosing instead to cordon off the city while compiling intelligence on the exact location of Baathist fighters. By the time a full-scale assault was launched on April 6, 2003, Basra fell with little damage to civilians. The British immediately "began to adopt a postwar mode": "they took off their helmets and flak jackets, dismounted from their armoured vehicles and began to mingle with the crowds."

That soft approach is relatively easy to follow in an area populated by friendly Shiites; it's much harder to act that way in the Sunni Triangle, where the U.S. military has suffered the bulk of its casualties in the past year. While Keegan is mildly critical of some U.S. missteps, he ends the book with a ringing defense of the war, which, he writes, made "the world . . . undoubtedly a safer place." Let us hope that subsequent events do not invalidate that cheerful conclusion. *

Max Boot, a senior fellow at the Council on Foreign Relations, is author of "The Savage Wars of Peace."

A U.S. soldier watches as a statue of Iraq's President Saddam Hussein falls in central Baghdad on April 9, 2003.