Trailer for Manoel de Oliveira's 1990 film 'Non', ou A Vã Glória de Mandar / No, or the Vain Glory of Command:
2 IMDB user comments makes this seem like Oliveira's anti-colonialist masterpiece:
"Episodes from entire military history of Portugal are told through flashbacks as a professorish soldier recounts them while marching through a Portuguese African colony in 1973. He easily draws his comrades into philosophical musings, and the little contingent suffers badly at the hands of the local military opposition."
"The movie starts in the beginning of the end the of Portuguese Colonial Empire, illustrating the discontent of Portugueses Arm Forces concerning the development of the war in the Portuguese Colonies. At the same time, it demonstrates, in the words of a young Portuguese soldier (as a way of explaining why they are there,in the war), the evolution of the existence of Portuguese State (as a concept or an idea of building independent State). Which shows from Viriato (considered the "first Portuguese" to fight for the independence of the Roman province of Lusitania which now constitutes currently part of Porugal) passing by D. Sebastião (that was a Portuguese king that had a dream of building a Christian empire in northern Africa; from there reconquer the holy land, and after that crowned himself Pope of all Christianity and then overthrown the Pope in Rome)... It's a very profund film, and I consider it a one of the greatest achievements of the Portuguese moderno cinema."