Horror and gore, honour and glory: 'Hacksaw Ridge' and the war film

Why do viewers flock to cinemas, year in and year out, to catch the latest war flick? With reference to Mel Gibson's 'Hacksaw ridge', which dramatises the real-life heroism of American Medic Desmond Doss, Elizabeth Flux investigates the enduring appeal - and ethical ambivalence - of the subgenre.