"Dishonored", 1931 film with Marlene Dietrich as an Austrian spy.

[Moonraker]

See it here.

Director Josef von Sternberg and a fresh-faced Marlene Dietrich deliver a worthy film, though Victor McLagen is miscast as a dashing, womanising Russian colonel (a role intended for Gary Cooper).

Marlene plays a. Austrian war widow in 1915 working as a patriotic prostitute, who is recruited by the chief of Austrian intelligence, played by Gustav Von Seyfertitz, to get proof that a  field marshal is a traitor and then to seduce a Russian colonel. Made before the Hays Code toned down American films, there's quite a bit of implicit sexuality - though did Austrian women really wear such short skirts in 1915-16?

Apart from her putting over a lot of sensuality, there's a curious comical episode where, as a simple cleaner in the Russian officers' base, she's chased around by a lecherous officer miaowing at him and clambering up on to a cupboard.  Such is the contrast with her sophisticated persona in the rest of the film that at first I thought it was another actress.

IMBD

(When the First World War broke out, McLaglen joined the Irish Fusiliers and soldiered in the Middle East, eventually serving as Provost Marshal for the city of Baghdad. We have at least two threads about him.)