The filmmaker Peter Jackson deserves more than an Oscar; he deserves a medal.

What the director of the “Lord of the Rings” and “Hobbit” movies has done with his World War I documentary, “They Shall Not Grow Old,” is more than restore archival film; he has restored the humanity of men caught up in one of history’s great cataclysms. This is an aesthetic achievement of the highest order, and a great service to history.

World War I has always had more than its share of historiography, novels, poems and feature films. Until now what it lacked was video (at least watchable video), the single most powerful medium of the modern era.

It took Jackson and his team five years to make “They Shall Not Grow Old.” They had to painstakingly remove scratches and other damage from old film belonging to the Imperial War Museum, and slow down the primitive footage. Then it was colorized, with loving accuracy. Forensic lip readers recovered what soldiers were saying on the film, and actors provided the voices. Finally, it was made 3D.

The effect is to transform the men originally caught on choppy black-and-white film to relatable, individual human beings, just like anyone else we watch on a screen today.

World War I was such an industrial-scale event that it tends to become impersonal, the men who fought it reduced in our minds to cannon fodder.

Jackson’s artistic choices open up a new vista. He focuses only on British soldiers on the Western Front and doesn’t retell the events of the war. There is no narrator and no historians. Instead, the voices of vets interviewed by the BBC in the 1960s and ’70s constitute the narration. They tell the story of their personal experiences from enlistment to the end of the war.

This lends an astonishing cinematic intimacy to life on the front. We hear about soldiers’ preferences in cigarettes, how they fried bacon on the front line, their method of warming up water for tea via machines guns, how they went to the bathroom (the less you know, the better), and their astonishment at the prostitutes in French villages.

There are plenty of hellish details. The constant small of death. The lice that, after their eggs are meticulously burned off uniforms, return the next morning. The rats that, fat from eating corpses, infest the trenches. The sucking mud of winter that is potentially fatal with the wrong step.

Yet what is most striking about “They Shall Not Grow Old” is how many grins there are. The vets, who were just kids at the time, say that they joked constantly. Really, what else were they going to do, except try to make the best of it? One vet compares the times of relative quiet to an outdoors trip among friends with just enough danger to make it interesting. That Jackson recovers this neglected part of their story is a key part of his contribution.

Not that there is any stinting on the horrors. The descriptions of battle are unadorned and hauntingly specific — the mind-numbing artillery barrages, the fearful waiting before going over the top, the walking (yes, walking) across no man’s land, the battle plans gone terribly awry, the shattered bodies all around, hand-to-hand combat with the Germans.

Still, amid the carnage, the humanity of the soldiers is undimmed. When they capture Germans, they tend to get along. German prisoners spontaneously take up stretcher duty, carrying the British wounded to make themselves useful. The underlying attitude is that they are all boys, thrown into this maelstrom by forces beyond their control.

When the war ends, the soldiers return to a civilian society that doesn’t know what they experienced. The vets talk of it only among themselves, believing that no one else will understand. A hundred years later, Peter Jackson has set to prove them wrong with a masterly act of filmmaking and historical memory.

Rich Lowry can be reached via email at comments.lowry@nationalreview.com.

• By RICH LOWRY