Operator 13

Operatoris a 1934 American romance film directed by Richard Boleslawski and starring Marion Davies, Gary Cooper, and Jean Parker. Based on stories written by Robert W. Chambers, the film is about a Union spy who impersonates a black maid in the early days of the Civil War, but complications arise when she falls in love with a Confederate officer. The film received an Academy Award nomination for Best Cinematography.

Gail, disguised in blackface, accompanies Pauline as her octaroon black maid. While washing General Stuarts clothes, she hears he will attend a ball that night. At the ball, Captain Gailliard suspects that Pauline is a spy and finds evidence in her room. Pauline, trying to flee, is arrested and is to be a witness against Gail, who is later sentenced to death. Both women manage to escape and return to the Union lines.Pinkerton decides to use Gail to trap Gailliard, and as part of the plan, she jeers at a parade of Union soldiers and is thought to be a heroine in the southern newspapers. Gail, as Anne Claibourne, is pardoned by Lincoln and heads south, where Captain Gailliard is attracted to her. However, Gail is later told by Stuarts groom, a fellow spy, that she is known to be a spy and she flees in a Confederate uniform. Gailliard cannot believe she is a spy and finds her, but she strikes him with a gun and rides off. Others start in pursuit. ........

Source: Wikipedia