In what new way were movies used during the great depression and world war 2?

Movies were often used as political propaganda. For example, during world war 2, movies shown were either about the war or were actual scenes from the war using footage by people on the war fronts. This was done to improve morale and inspire people to join the effort. The movies would be about monstrosities by the enemies and about war heroes of the allies and the people would join the fight and want to help.