The early films of Sergei Eisenstein that propagandize communism and the Russian revolution. Battleship Potemkin, Strike, and October are the three that I have in mind (and have actually watched). Strike is the weakest, but has some more intimate and personal tones as well as some excellent naturalistic shots of daily life at the time. Battleship Potemkin is the most famous and retells the mutiny of the titular battleship during the 1905 uprising. October is really excellent and probably the height of Eisenstein synthesizing high-art film-making with a revolutionary purpose, but I think it may have been censored due too being to abstract for the purpose of the film that he was asked to make. (Not sure if censored is the right word, sometimes western resources apply the word very liberally.)

All these films are available without copyright, though the best viewing experience is to track down a DVD (check the library!) as these predate synchronized scores. A physical reissue of a public domain film from the early silent era often budgets in producing a decent score, which is expressly not PD. Some versions available on the internet have poor-quality scores or even AI generated audio.