War film
A war film is any film dealing with war, usually focusing on naval, air, or land battle, but sometimes focusing instead on prisoners of war, covert operations, training, or other related subjects.
Many of the dramatic war films in the early 1940s in the United States were designed to create consensus at the expense of "the enemy." In fact, one of the conventions of the genre that developed during the period was that of a cross-section of the United States which comes together as a crack unit for the good of the country.
War films (like films in any genre) tend to have a number of cliches associated with them: for instance, in a war film, a small group of men will tend to be fairly diverse ethnically, but most of the characters will not be developed much beyond their ethnicity; the officer immediately ranking the main character will tend to be both unreasonable and unyielding; almost anyone sharing personal information--especially plans for after returning home--will die shortly after sharing the plans; and anyone acting in a cowardly or unpatriotic manner will either convert to heroism or die.
See also: propaganda, genre film theory