The Ascent (1977)

Winter 1942. Byelorussia (now Belarus) is occupied by the Nazis. Two partisans are taken prisoner. After brutal interrogations, one of the men agrees to cooperate. He justifies the betrayal to himself as a temporary measure, hoping to escape and rejoin the partisans in fighting. Playing a double game, the hero fails to notice how he personally kicks the support out from under his comrade-in-arms on the gallows… 

The movie received the highest award at the Berlin Film Festival in 1977. It’s based on the novella by Vasil Bykov and also inspired by real events.