One of the first things you notice in "They Shall Not Grow Old" - a remarkable new World War I documentary that uses restored footage from more than 100 years ago to tell the story of the men who fought in what has come to be known as "The Great War" - is the teeth.

It's certainly not the only thing. But when director Peter Jackson ("The Lord of the Rings") took this often grainy black-and-white silent footage from hand-cranked cameras and sharpened it, colorized it, added sound and digitally tweaked the speed to compensate for today's faster frame rates, several interesting things happened. One of them is that you suddenly can't help notice how many of the film's subjects – anonymous British infantrymen, in this case – are missing teeth here and there.

Could it be a result of the fact that these soldiers, as we learn from the film, were issued a single toothbrush to use during their entire tour of duty, and that they just as often used it to scrub the mud out of their uniform buttons as they did for oral hygiene?

It's a minor detail in a film that is filled with them, one of many fine points that cumulatively add up to a powerful and moving portrait of war and its consequences.

Commissioned by England's Imperial War Museums to commemorate the centennial of the 1918 armistice, and exclusively using footage from that organization's film archive - along with oral histories recorded by WWI veterans in the 1960s and 1970s - "They Shall Not Grow Old" is a major technical accomplishment. But it's also a major feat of storytelling, one that mentions no dates, place names or famous battles, yet nevertheless manages to evoke a profound sense of connection with its nameless subjects.

Moving from enlistment to boot camp to the nightmare of trench warfare on the Western front, the film uses its freshly enhanced imaging (available in 2-D and 3-D screenings) to make the mundane horrors of war - lice, corpse rats, flies, open-air latrines - as vivid as the more hellish ones: the hailstorms of bullets, clouds of yellowish mustard gas, trench foot, gore and shattered bodies.

It's an unexpectedly contemporary-feeling experience, in large part because of the way the faces on the screen seem to reflect those in the audience. Is it simply an effect of the colorization, which reminds us how pink is the flesh of youth, and how red its blood? For whatever reason, "They Shall Not Grow Old" has the effect of a window that has never before been thrown open so wide.

This comes as a bit of a revelation, about 10 or 15 minutes into the documentary, which begins like every other one on WWI you've ever seen: with a squarish frame of blurry, herky-jerky black-and-white footage and canned-sounding voice-over. Then, all of a sudden, the frame expands to a widescreen view, with ambient sound added: shells exploding in a ravaged landscape; the mingling voices (and footsteps) of marching troops; laughter; shouts; and even music at times.

It is, in short, a portrait of humanity and inhumanity. The way Jackson presents both here, it's easy to see why the world thought this conflict would be the "war to end all wars." And it's acutely painful to realize that it has not.

'They Shall Not Grow Old'

Four stars out of four. Rated R. Contains disturbing war images. 99 minutes.