Is the movie 1917 (2019) based on a true story?

No, the movie 1917 is not based on a true story. The film is a work of fiction that follows two British soldiers in World War I who are assigned a dangerous mission to cross enemy lines and deliver a message that could potentially save the lives of 1,600 men. However, the film is inspired by the real-life experiences of director Sam Mendes’ grandfather, who served as a messenger during the war.