'The Duellists' - one of Ridley Scott's first films. It revolves around two army officers in the Napoleonic wars who manage to challenge each other to a duel. This business goes on for decades - they just keep bumping into each other but never get around to settling their differences.
In the end they decide to call it a day. They're getting on by this time and wise enough to realise it was pointless and absurd.
But it isn't the story that makes it a masterpiece but the authenticity that Ridley Scott brings to it.
He never managed to repeat the craftsmanship when he made 'Alien'. Unfortunately.