During 15 hours over seven nights, Ken Burns' much-awaited documentary immerses us in World War II.

The enormity of that war — which placed the world's future in doubt while claiming at least 50 million lives — is something most of us take for granted, even with it shrinking in the rearview mirror of our collective consciousness.

But Burns' "The War" means to restore it to the here-and-now for us to see with new eyes. And he does it in a way that, by now, many viewers expect, even count on: By giving it the Ken Burns treatment.

Story-driven and deliberate, yet lyric. Sweeping in scope but highly personal. Very, very long. These are words applied to his past miniseries, huge-topic films like "Jazz," "The West," "Baseball" and "The Civil War."

The same adjectives fit "The War," which interweaves the European and Pacific conflicts, braided with the war experience here at home. (Co-produced and co-directed by Burns and Lynn Novick, it airs on PBS tonight through Wednesday, then Sept. 30 to Oct. 2.

"The War" has been in the works since 2000. Burns began it before 9/11 and, thus, before the Iraq war, which has given his film bleak, unanticipated currency.

How did he begin such a mission?

"Intimately, always," he says.

The first step was choosing four American towns to draw from: Mobile, Ala.; Sacramento, Calif.; Waterbury, Conn.; and the tiny farming community of Luverne, Minn.

"We picked them, more or less randomly, then went to those towns and learned everything we could about them and the people who lived there," Burns says.

Burns begins his massive saga almost microscopically — with Glenn Frazier, who was a 16-year-old Alabama lad in 1941.

With obvious wonder, Burns, 54, describes Frazier's war years: "His girlfriend since the first grade says, 'Well, I like you as a friend, but ...' The next day, he volunteers for the Army, and he's sent to the Philippines, where he's in the Bataan Death March, and then digging his grave for his imminent death, and then a POW in Japan for years. And then, the next moment, he's home.

"The whole war," says Burns, "is contained within the arc of his experience."

Six decades later, Glenn Frazier (along with some 40 more witnesses) is on the screen to tell us about it.

The people Burns has interviewed give "The War" its immediacy — and reaching them in time only heightened the urgency for him to make his film.

A thousand veterans are dying each day, says Burns. "In a few more years, they will be gone. Then the Second World War will be the province of historians, who, however well, will nonetheless be abstracting it."

The four towns (and the stories their citizens tell) provide the driving force of "The War." That's what defines it, regardless of who these witnesses are.

But the film tells a collective story that unfolds grandly, horribly, painfully, proudly. It exposes the gaping divide between that era and the current day, while mounting a mighty effort to bridge it.

"The War" is a towering tribute. But the war Burns marshals us through is necessary — not, as some might prefer to think, "good." This film, however big-hearted, is no sentimental journey.

By the end, those who watch "The War" may find they share a bit of what the man who made it feels.

"This," says Burns, "is the first film that I haven't wanted to let go of."