In April 1945, the Supreme Headquarters Allied Expeditionary Force ordered that footage shot by combat and newsreel cameramen during the liberation of Occupied Europe be aggregated into a documentary film that would be shown to the German prisoners of war as irrefutable proof of what had occurred under the Nazi regime.The producer from the British Ministry of Information, Sidney Bernstein, assembled a first-rank team of editors for the project and eventually brought Alfred Hitchcock over to help organize the footage and accompanying narration. (Later, Billy Wilder would also be brought in to work on the documentary.)

Post-war events quickly overshadowed the painstaking work. The last official action on the film, according to the Imperial War Museum in London, was a screening of the five-reel rough cut on September 29, 1945, after which it was shelved. Seven years later, the material, including 100 more reels of unedited footage, a script for the narration and the shot list for the planned film, were turned over to the Imperial War Museum. Some of it was used in "Memory Of The Camps," which was shown at the 1984 Berlin Film Festival and, a year later, on the PBS documentary series "Frontline." It wasn't until 2008 that work began in earnest to restore the five reels and complete work on the unfinished sixth.

The resulting film has the unglamorous yet unassailably apt title "German Concentration Camps Factual Study." HBO has begun showing "Night Will Fall," a documentary about the making of the documentary that includes several minutes of the footage. On Tuesday night, Deadline saw the complete film in Los Angeles at the Museum Of Tolerance, an arm of the Simon Wiesenthal Center. The museum co-sponsored its American premiere in connection with International Holocaust Remembrance Day on this 70th anniversary of the liberation of Auschwitz. The audience included representatives from various foreign consulates, clergy and community leaders, and a number of survivors with first-hand knowledge of what we were about to see.

The film opens with a brief introduction showing Hitler's rise to power, with the streets packed, a thousand Times Squares on New Years Eve, with roaring crowds saluting Der Fuehrer and row upon row of swastika-emblazoned flags waving in the wind. The scene shifts quickly to the picturesque town of Belsen and the camp there, where smiling children greet the cameras before we are confronted with mountains of the dead — skeletal remains barely recognizable as human — among the well-fed German officers and grinning women the village cheerfully serving as volunteers in the camp.

The film is unabashedly shocking in its clarity of detail and lack of squeamishness. The battle-worn cameramen took great care to record what they witnessed so as to obviate any possible charge that the footage was staged. There are long, uninterrupted shots of indescribable inhumanity, of impossibly starved bodies, hollowed cheeks, dead eyes open wide and smashed skulls; of the officers and town folk forced to by the Allied troops to drag the surreal stick figures from the typhus-breeding barracks or frozen ground where they lay snow-covered and naked, to the pits that had been bull-dozed for mass graves, each marked with an estimated number of the bodies within: 5,000 in one plot after the next. The cameras movie unblinkingly into the gas chambers, with their Zyklon cannisters, and crematoriums still smoldering and filled with ash and bone.

Even more difficult to see are the survivors, many too sick from disease and starvation to have any hope of recovery. In Dachau and Mauthausen and Majdanek, among other notorious camps, the mountains of the dead are contrasted with scenes of listless haunted men marching naked and freezing; of women having their first hot showers and choosing fresh clothes, of children being handed a square of chocolate and a bowl of soup.

The original commentary and narration has been recorded by actor Jasper Britton. The digital remastering of the film included piecing together the missing sixth and final reel according to the shot lists and script; the work was overseen by Dr. Toby Haggith, restoration director and senior curator at the Imperial War Museum, and George Smith, the restoration editor.

I suppose the calculus of horror varies from one of us to another.We all have our limits; for some its a mouse in the kitchen, for others, the opening scene of "Saving Private Ryan." But I can't imagine anyone finding "The German Concentration Camps Factual Survey" other than nearly impossible to watch. Not long after the film began, I heard weeping from the couple sitting in front of me, both of them survivors there by invitation. The husband, sobbing, kept telling his wife not to look, shielding her eyes lovingly. Yet he was the one who finally whispered, "I wasn't prepared for this" as he reached for his walker and quietly left the auditorium. A few minutes later, his wife followed. I would say I know how they felt, but of course I have no idea. I do know how I felt, which was taken to the edge of a bottomless chasm. It was almost impossible to walk out into the night.