Infamous as the torturously long documentary that Woody Allen insists on taking Diane Keaton to in Annie Hall, The Sorrow And The Pity deserves a more polished reputation as a cinema classic. Condensing over 80 hours of footage into a four-hour film about the Nazi occupation of France, director Marcel Ophuls offers an exhaustive collection of interviews, archive footage and newsreel clips. It may sound tedious, but it's actually a captivating achievement.

"IT HAS LOST LITTLE OF ITS CHALLENGING IMPACT"

Released in French cinemas in 1971 after the French television station it was produced for refused to screen it, The Sorrow And The Pity became an overnight sensation. A quarter of a century after the end of the war it was considered incendiary and intolerable. Even today it's lost little of its challenging impact.

Set in two parts - The Collapse and The Choice - Ophuls' film interviews surviving members of the French town of Clermont-Ferrand about their experience of the Occupation and the Vichy regime. Were they collaborators, resistants, or pro-Nazis? Or were they simply mute bystanders?

The answers are never simple. An old farmer talks about being interned at Buchenwald concentration camp after a neighbour reported his resistance activities. A British agent who parachuted into Vichy France tells of falling in love with a German soldier. Pro-Nazi Frenchmen talk in disturbingly unrepentant tones about their hatred of Communism and the absolute perfection of the German army.

More than just a series of nattering heads, Ophuls' film investigates history, memory, and truth. Although he never explicitly judges his speakers, Ophuls often undercuts their assertions, showing archive footage that contradicts their claims or setting their testimony next to the strikingly different recollections of others.

What stands out is just how few people took up arms against the invaders. Partly that was out of fear, yet partly also out of a misguided belief that it was all for the best. It begs a distressing question. Churchill may have been convinced that the British would "fight them on the beaches... in the hills and in the streets", but after watching this gripping story of a nation's collapse, you can't help wondering if we'd have reacted any differently than the citizens of Clermont-Ferrand.

In French with English subtitles.