Van Johnson is good in Battleground. But he's not "the star"--it's an ensemble piece.

The one who always gets discussed with that film is James Whitmore.

From the wiki:

Battleground won two Academy Awards: for Best Cinematography, Black-and-White (Paul C. Vogel) and for Best Writing, Story and Screenplay (Robert Pirosh). It was also nominated for Best Picture, Best Director (William A. Wellman), Best Film Editing (John D. Dunning), and Best Actor in a Supporting Role (James Whitmore). James Whitmore won a 1950 Golden Globe Award as Best Supporting Actor, and Robert Pirosh's script won Best Screenplay. Pirosh was also nominated for a Writers Guild Award for Best Written American Drama.