This was shown on TCM (Turner Classic Movies).
Set in a post-war Paris is the sergeant in question, one who has high standards and he believes, high morals. When he takes over a new set of men, they're sloppy, of low morale and in his eyes, weak and lazy.
He is naturally drawn to a young private, played by John Philip Law. Pte Tom Swanson (Law) has a sweet, French girlfriend but Master Sgt Albert Callan (Steiger) isn't interested in her, or women generally. He'd been married before but that fell apart.
Sgt Callan doesn't seem to show signs of his homosexual attraction to Law in the physical sense, but as mentor, friend and drinking buddy. Initially, he enlists him as the regiment's clerk, in effect his personal secretary, though Law tries to resist having to do that sort of work.
It's quite refreshing after all those Vietnam war movies where Sergeants are only shouting sadists, who beat their charges into total mental submission. However, this is not sweet nothings whispered over candle- lit dinners either, Steiger for all intents and purposes is a man's man. One, whom perhaps has lost his purpose, particularly in the Army, where they act now only as peacekeepers.
The film itself is quite slow and methodical and not really for a modern audience. But, for a character-driven drama, with Steiger both convincing and good, it passes muster. The script follows in the same vein as the direction.
It must also have been quite a brave role for Steiger to take as its subject was still taboo, especially in the macho world of the Military and any associations with that taboo could seriously affect an actor's reputation. The fact that Amazon don't list it as a region 2 DVD means that it must be a little-seen rarity. Kind of understandable. But, if you can catch it on TV, it's worth a look, I'd say.