Most of us have seen film footage of the concentration camps. Just the mention of them conjures up in our minds the piles of corpses, or the ovens. In the immediate postwar years, those images were new for most people, and even more shocking than they are for us now. Army film crews recorded thousands of hours of footage in an attempt to capture the scope of what happened.

The Allies guessed surprisingly early how important it was to present proof of the  atrocities in the form of film. The Germans were to see what they had allowed under the Nazi regime, and the world at large was to see the unthinkable acts committed in the shadows of an already dark war.

Earlier this year, HBO broadcast Night Will Fall, a look at what happened to the “German Concentration Camps Factual Survey,” a dry name for a horrific compilation of footage of Bergen Belsen, Auschwitz and Dachau. Alfred Hitchcock supervised the production, but his big name wasn’t enough to keep the project afloat. The British government canceled, and the footage was stored at the Imperial War Museum until it was unearthed in the 1980s, then digitized and restored in 2010.

Why was the original project canceled? “Night Will Fall” director André Singer told the LA Times that postwar priorities shifted quickly; the British saw the need for Germany to get back on its feet (no doubt in the face of the Soviet threat). Reminders of the camps wouldn’t help.  Authorities also worried the footage of the camps would create more sympathy for the Jews wanting to go to Palestine, a difficult political topic before the founding of Israel.

Some of Hitchcock’s footage was recycled for Billy Wilder and Hanus Burger’s short, finished documentary Death Mills, which was shown in the US and British Zones of Germany in 1946. Pregnant women were warned not to go see it.

Ten years after the end of the war, Alain Resnais directed what I consider one of the most moving films about the camps, Night and Fog. I saw it in high school and have never forgotten it.