Revolt of the Zombies (1936)

The opening text scrawl of this film refers to "the World War", which was accurate enough at the time it was made but is a little jarring to read now.  Less accurate, to the best of my knowledge, is the film's reference to the "Franco-Austrian front".  France and Austria-Hungary did not share a border.  Perhaps they mean the Italian front, where French troops did support the Italians against the Austrians.

In any case, on the probably non-existent Franco-Austrian front is a French Cambodian unit.  A mere handful of soldiers from this unit prove able to overrun an entire Austrian trench.  You'd think that would be cause for celebration on the Allied side, but it is not.  The troops in question, you see, are zombies, under the control of a Cambodian priest. They are not actual undead, but living men under voodoo style domination that makes them fearless and immune to pain, but without will of their own.

The priest's unnatural powers seem like a threat to white domination, and so the French conspire with their Austrian enemies (!) to imprison him.

Before they can, however, he is murdered.  Without any way to be sure if the zombification rituals died with him, the supposed enemies set off to Angkor Wat (clearly actually a soundstage) to see if any other knowledge of the process exists.

You're probably thinking that the collaboration between enemies will break down, with the Austrians (as enemies of the US during the war) wickedly trying to gain control of the process to shore up their faltering armies.  But that would be far too obvious - and sensible - for this film.

Instead, one of the French officers - who has more or less appeared to be the protagonist so far - loses the woman he loves to someone else.  So he turns zombie master, enslaving everyone around him: including the man his romantic fixation chose instead of him.

Eventually, hoping to finally win over the girl of his dreams with a dramatic gesture, he relinquishes his control on all this slaves.  I'm not sure that "Sorry about zombifying the guy you love.  Wanna bang?" is actually going to work out too well as a seduction technique, but he won't live long enough to find out - the folks he enslaved wreak fatal revenge upon him instead.

And then the movie ends, thankfully, sparing me from having to watch it any longer.