Watched this a couple months ago. The entire film is in Youtube with English subtitles.

A Portuguese military convoy moves through an African colony in the waning years of the Estado Novo. Its bored soldiers begin to discuss their war, with varied opinions: one is a cynic, one is a patriot and one seems to sympathise with the opposition. Their conversation fails to break into new ground or reach any conclusions. Ensign Cabrita, a more intellectual soldier, derails their talk by narrating the tragedy of Viriathus. As Cabrita proceeds to speak of more events in Portugal's past, they spend almost the entire rest of the film immersed in serious philosophical and metahistoric discussions. The legacy and purpose of an empire is debated. The notion of fate is strongly present: it is said that Portugal's fate was to be conquered by the Romans, to fail in its bids for expansion within Iberia, to explore the seas.

The soundtrack is good and the scenes are subtle but beautiful. Nonetheless, towards the middle it becomes too slow and weak, and only at the end it regains steam and becomes grandiose.