Les Carabiniers (Jean-Luc Godard, 1963)

Couldn't be anyone other than Godard, and yet not sure I've ever seen a film with quite this mix of humour (which somehow isn't really black humour) and bleak savagery. Might be interesting to consider why a bunch of young directors at (very) roughly the same time made black and white allegorical war films: as well as this Kubrick's Fear and Desire (the outlier in time, being from 1953); Tarkovsky's Ivan's Childhood (1962); and Herzog's Signs of Life (1968).