The Bugle Sounds

The Bugle Sounds is a 1942 American World War II movie starring Wallace Beery as a cavalry sergeant resistant to replacing horses with tanks. The supporting cast includes Marjorie Main, Lewis Stone, George Bancroft, Donna Reed, and Chill Wills, and the film was directed by S. Sylvan Simon.

Plot
In 1941, Colonel Lawton of the 19th Cavalry Regiment has to convert his unit from horses to light tanks. First Sergeant Patrick Aloysius 'Hap' Doan who has nearly 30 years in the US Cavalry with service in the Mexican Border Campaign and World War I has a hard time with the adjustments. The regiment is also to take in its first draftees. In the meantime saboteurs are attempting to destroy the tanks.