When a steadily shrinking legion of veterans musters on the Mall this weekend to dedicate the National World War II Memorial, rarely will so few be owed so much by so many.

The size and central location of the memorial -- 71/2 acres, midway between the Washington Monument and Lincoln Memorial -- imply the monumental nature of the war it commemorates: the largest, most catastrophic event in human history, at least since the Great Flood.

From the German invasion of Poland in 1939 until the Japanese surrender in Tokyo Bay in 1945, the war lasted 2,193 days and claimed an average of 27,600 lives every day, or 1,150 an hour, or 19 a minute, or one death every three seconds. In the time it takes to read this paragraph aloud, 10 people perished in World War II -- an estimated total of 60 million.

The new memorial is 21st century America's effort to capture, in granite and bronze and gilt lettering, the 20th century's central myth, "a vast imagining of a primal time" -- in the words of novelist John Updike -- "when good and evil contended for the planet, a tale of Troy whose angles are infinite and whose central figures never fail to amaze us with their size, their theatricality, their sweep."

Inexorably, the day is approaching when not a single human alive has a personal recollection of the war, which then will slide fully into mythology, history and collective memory. Although 16.4 million Americans served during the war, fewer than 5 million remain alive; the youngest survivors now are in their late seventies, and they are passing at the rate of 1,100 a day.

The memorial dedicated this weekend is part of that mnemonic migration, a tribute not only to those who served, or the 291,000 U.S. battle deaths, or the 670,000 U.S. wounded, or the tens of millions who labored in factories and fields and dockyards. It is an effort to convey, to generations hence, that the war was a struggle both about territory and, as the historian Gerhard L. Weinberg has written, "about who would live and control the resources of the globe, and which peoples would vanish entirely because they were believed inferior or undesirable by the victors."

It was a war that ranged across six continents, from those titanic, three-syllable battlefields that still serve as historical mileposts -- Stalingrad, Coral Sea, Anzio, Normandy -- to obscure fights in improbable settings rarely associated with the Second World War, places like the Aleutians, Madagascar, Syria and Darwin, Australia.

The war's origins lay in the 20th century's other global catastrophe, World War I, and in lingering resentments, unquenched hatreds and unresolved rivalries that metastasized through the 1920s and 1930s. In Asia, the growth of Japanese nationalism and militarism led Tokyo to seize huge areas in Manchuria and north-central China. The parallel rise of fascism in Italy and national socialism in Germany also fueled aggression and brutal repression. Italian imperial ambitions in the 1930s stretched as far as Abyssinia in East Africa, while Germany annexed Austria and then swallowed part of Czechoslovakia through raw intimidation.

With Germany's invasion of Poland on Sept. 1, 1939, the conflagration began. Within four weeks of that blitzkrieg attack by 60 German divisions, the lightning war had killed 140,000 Polish soldiers, as well as 25,000 civilians in various bombing attacks. An additional 10,000 civilians -- mostly middle-class professionals -- had been rounded up and murdered, and 22 million Poles now belonged to the Third Reich. "Take a good look around Warsaw," Adolf Hitler told journalists during a visit to the shattered Polish capital. "That is how I can deal with any European city."

France and Great Britain had declared war against the German aggressors Sept. 3, but fighting subsided for six months while Hitler consolidated his winnings and plotted his next move. That came in early April 1940, when Wehrmacht troops seized Denmark and attacked Norway. A month later, 136 German divisions swept into the Netherlands, Belgium, Luxembourg and France. Winston S. Churchill -- a short, stout, lisping politician of indomitable will and linguistic genius, who on May 10 became the British prime minister -- told President Franklin D. Roosevelt, "The small countries are simply smashed up, one by one, like matchwood."

The fascist powers yoked themselves together in a murderous alliance known as the Axis. Hitler invaded the Soviet Union in June 1941, struggled to obliterate British resistance and began a systematic campaign to exterminate those considered inferior or undesirable, a holocaust that cost the lives of 6 million European Jews and countless gypsies, homosexuals, socialists, communists and others who contradicted Aryan ideals.

The American war can be summarized in a paragraph: After the Japanese sneak attack on Pearl Harbor on Dec. 7, 1941, the United States -- in alliance with London, Moscow and others -- resolved to first crush Germany, the strongest of the Axis partners, and to then defeat Japan. A brutal but successful seven-month campaign to occupy North Africa -- and thus regain control of the Mediterranean Sea -- was followed in mid-1943 by invasions of Sicily and the Italian mainland. Island-hopping thrusts in the Central and Southwest Pacific brought U.S. air power within range of Japan, with devastating results. The invasion of France on June 6, 1944, and southern France two months later, squeezed Germany between the Anglo-Americans from the West and the Russian juggernaut from the East. Adolf Hitler's suicide, on April 30, 1945, was followed eight days later by Germany's unconditional surrender. Japan followed suit after a new American weapon, dubbed the atomic bomb, obliterated Hiroshima and Nagasaki in August.

Such summaries hardly do justice to the cause. It has been suggested that war, next to love, has most captured the world's imagination, and World War II remains particularly compelling for both its magnitude and for the clear moral imperative in the struggle against evil.

The Axis powers "failed because they repudiated human values and human faith, and from that repudiation flowed all the consequences that led to final defeat," historian Henry Steele Commager once wrote. "Against wickedness and terror and hatred, the free peoples of the world fought back. Their courage was a match for the force of the enemy, their ingenuity for his cunning, their free industry for his slavery, their faith for his cynicism."

Certainly the war defined an epoch of cunning and miscalculation, of sacrifice and self-indulgence, of ambiguity, of love, of malice and mass murder. It was a time when heroes came forth, but it was not an age of heroes if that implies universal nobility and statuary as clean and white and lifeless as alabaster. For many American veterans -- infused with the irony and skepticism that soldiering often nurtures -- the notion that they embody the greatest generation seems fatuous. In part that reflects rival claims from both the Founding Fathers and the Civil War generation, but it also reflects a realization that the war was too immense to be confined to a single generation: The senior military and civilian leaders mostly were born in the 1880s and 1890s -- Roosevelt in 1882, for example, Dwight D. Eisenhower in 1890 -- while the trigger-pullers mostly were born in the 1910s and 1920s.

The war also shaped a world. Its technological legacies include radar, jet airplanes, ballistic missiles, computers -- first developed to enhance code-breaking -- nuclear weapons, various medical miracles and industrialized genocide.

No less profound, World War II strangled the sinister ambitions of Germany, Japan and Italy; signaled an end to the British and French empires; politically fractured both a continent -- Europe -- and individual countries, such as Korea, Vietnam and Germany; led to the creation of both the United Nations and NATO; and yielded a bipolar world of Soviet and U.S. superpowers that persisted for a half-century.

"World War II had been about liberty," writer Mark Arnold-Foster has observed, and the Big One spawned independence movements and colonial wars that led to the creation of modern India, Pakistan, Ghana, Burma, Kenya, Israel and other states in a fermentation that continues to this day.

Domestically, the United States would never be the same. Although women accounted for only 2 percent of Americans in uniform, and blacks generally received second-class treatment in the armed forces, their vital roles in the nation's war effort created new opportunities and stirred new ambitions, fueling both the equal rights and civil rights movements.

Moreover, as the only major power to avoid devastating war damage at home, the United States emerged as an economic and military colossus. "Americans became involved commercially as well as diplomatically with the rest of the world to an extent that had no precedent in American history," Arnold-Foster wrote. "The new circumstances in which the United States found itself, including its new wealth, had made isolationism impractical as well as out of date."

Somehow the new memorial will attempt to embody all of this: sacrifice, ingenuity, determination, faith, change and the rise and fall of generations. Perhaps because it is so ambitious, the project has been a long time coming. Legislation calling for construction of a World War II memorial was first introduced in Congress in 1987 and eventually was signed into law by President Bill Clinton in 1993. Amid protracted wrangling over the location and design -- "How the hell did we ever win World War II?" an exhausted architect wondered after one particularly contentious planning session -- the site was consecrated in 1995 with soil from 16 American war cemeteries.

The neoclassical array of arches and fountains, framing a sunken plaza, is the latest of more than 150 memorials now seeding Washington. They range from the obvious (Thomas Jefferson and Ulysses S. Grant) to the improbable (Maine lobstermen and Dante) to the obscure (landscape architect Andrew Jackson Downing and the father of homeopathy, Samuel Hahnemann). But only about one-third sit within what planners call Area I -- the city's monumental core -- and few occupy a more visible site or commemorate a more signal event.

To be an enduring success, this memorial must "respond to a very simple question that a 15-year-old high school student who comes to Washington asks the teacher 100, 200 years from now," Friedrich St. Florian, an Austrian-born architect who won the memorial design competition, said in an interview several years ago. "So what was World War II about? How was it different from the Mexican war, or the Spanish war, or World War I?"

Part of that answer can be found in the assessment of the British historian Martin Gilbert: "Although the Second World War is now far distant, its shadows are long, its echoes loud. How else could it be with an event, lasting for nearly six years, in which courage and cruelty, hope and horror, violence and virtue, massacre and survival, were so closely intertwined?"

And the inevitable and appropriate shedding of tears on the Mall this weekend will only confirm Gilbert's observation: "The greatest unfinished business of the Second World War is human pain."

Rick Atkinson is the author of "An Army at Dawn: The War in North Africa, 1942-1943," which won the 2003 Pulitzer Prize for history. His latest book is "In the Company of Soldiers: A Chronicle of Combat," a first-person account of the U.S. war in Iraq.

Jack Holman, 78, left, observes a moment of silence with fellow veterans who came in a group of more than 400 from Kentucky.A sunset-hued sky and the Washington Monument are backdrop for five of the 56 granite pillars representing U.S. states and territories during the war. Of the 16.4 million Americans who served, fewer than 5 million remain alive.A view from atop the Washington Monument shows crowds visiting the new memorial. About 800,000 visitors are expected for the four-day festival accompanying the dedication of the memorial.A bronze bas-relief panel, one of 24 that will eventually line the ceremonial entrance on 17th Street, depicts flight operations aboard an aircraft carrier.