Marcel Ophüls's 1969 four-hour examination of Vichy-era France. Banned from French TV for a decade for telling the uncomfortable truth.
From Wikipedia
The Sorrow and the Pity is a two-part 1969 documentary film by Marcel Ophuls about the collaboration between the Vichy government and Nazi Germany during World War II. The film uses interviews with a German officer, collaborators, and resistance fighters from Clermont-Ferrand. They comment on the nature of and reasons for collaboration, including antisemitism, Anglophobia, fear of Bolsheviks and Soviet invasion, and the desire for power.