The Court-Martial of Billy Mitchell is a 1955 American CinemaScope biographical drama film directed by Otto Preminger, and starring Gary Cooper and co-starring Charles Bickford, Ralph Bellamy, Rod Steiger, and Elizabeth Montgomery in her film debut. The film is based on the 1925 court-martial of General Billy Mitchell, who is considered a founding figure of the U.S. Air Force.

During the 28th Academy Awards, it received a nomination for Best Story and Screenplay for Milton Sperling and Emmet Lavery. The award, however, went to Interrupted Melody (William Ludwig and Sonya Levien).

Brigadier General William "Billy" Mitchell (Gary Cooper) tries to prove the worth of the Air Service as an independent service by sinking a battleship under restrictive conditions agreed to by Army and Navy. He disobeys their orders to limit the attack to bombs under 1,000 pounds from an altitude of greater than 5,000 ft. and instead loads 2,000-pounders. With these, Mitchell directs his aircraft to fly at 1,500 ft. and proves he can sink the ex-German World War I battleship Ostfriesland, previously considered unsinkable. His superiors are outraged.

Mitchell is demoted to colonel and sent to a ground unit in Texas. A high-profile air disaster occurs in which his close friend Zachary Lansdowne (Jack Lord) is killed in the crash of the dirigible USS Shenandoah. This is followed by a second disaster in which six aircraft crash after flying from a base on the California coast to Fort Huachuca, Arizona. They were poorly maintained because of lack of funds.

Mitchell is outraged by the tragedy and calls a press conference in which he harshly accuses the Army and Navy of criminal negligence and almost treasonable disregard of the air service. This results in a court martial in Washington, D.C. He is represented by his friend, Illinois Congressman Frank R. Reid (Ralph Bellamy), an advocate of air power in Congress. None of the officers hearing the case, which includes General Douglas MacArthur, are in the Air Corps. Reid makes little headway. His request to call witnesses on the merits of Mitchell's position are denied. He asks who preferred the charges against Mitchell, and receiving no clear answer he demands the appearance as a witness of President Calvin Coolidge as commander of all armed forces. The court adjourns to consider the request..

Mitchell refuses to sign a paper Reid has presented him in which he withdraws his criticisms in return for saving his career as an Army officer. Margaret Lansdowne (Elizabeth Montgomery), widow of Mitchell's dead friend from the Shenandoah, then appears in court. Coolidge declines to appear, but witnesses on air power previously excluded are now allowed to testify to corroborate Mitchell's criticisms, including Eddie Rickenbacker (Tom McKee), Carl Spaatz (Steve Roberts), Henry H. Arnold (Robert Brubaker) and Fiorello LaGuardia (Phil Arnold).

Finally Mitchell testifies and is cross-examined by Maj. Allen W. Gullion (Rod Steiger), a prosecutor specially brought in for the job. He stresses that Mitchell had disobeyed his superior officers. Gullion also ridicules Mitchell's claims, such as his prediction that Japan would attack the U.S. Navy at Pearl Harbor.

The court finds Mitchell guilty, however his men in the air service salute him as he departs. Mitchell steps out and looks up to see a squadron of four biplanes and fades to a squadron of fighter jets, demonstrating what Billy Mitchell's actions will result in for the future of the United States and its Air Force.

Producer and screenwriter Milton Sperling began work on Mitchell's story in 1938, just two years after the general's death. In the successive years, he continued to seek out help from Mitchell's family until 1955 when production began in earnest. Under the direction of Otto Preminger, the first 10 days of principal photography took place on location in Washington, D.C. in the original sites involved in the story. The old War Department Building, Army-Navy Club and State Department buildings, among others, were featured in key scenes.^[2]

Aerial sequences under the direction of second unit director Russ Saunders and aerial coordinator Paul Mantz took place at the Fletcher Airport in Rosamond, California. The aircraft that were used in the film included two Curtiss JN-4 biplanes, de Havilland DH-4, Grumman J2F Duck and Waco 10 biplanes.^[3]

The Court-Martial of Billy Mitchell had its national premiere in New York City on December 22, 1955 as the main feature along with the short 24 Hour Alert.^[4] The films, subsequently, were paired with the longer feature shown first in major cities.^[5] When The Court-Martial of Billy Mitchell was released, Mitchell's sister Ruth, who served in World War II with Yugoslavian Chetnik guerrillas and later wrote a book about her brother, toured the U.S. doing publicity for the film.^{[6][Note 1]}

• List of American films of 1955