Both sides used propaganda in WWI and WWII in order to demonstrate that their side was in the right in the war, or that their side would come out victorious. Propaganda is information used to promote a certain political or point of view. Britain and France won the propaganda war in WWI in that the Royal Navy cut Germany's transoceanic cable, thus ensuring mainly Allied-favorable news reached America. When Germany invaded Belgium and started to attack partisans, which was in their right to do, Britain and France issued out posters and films showing the German as a barbaric Hun who was intent on wiping out civilization. When America entered the war, it quickly followed suit by creating films and posters showing the German as either a barbaric savage or an inept fighter. Also, women appeared prominently in these films and posters in an attempt to appeal to masculinity in order to get more soldiers to "protect the women."
Germany was better equipped in propaganda in WWII. German posters showed the Allies as decadent, and the Germans even made a movie that showed the sinking of the Titanic as being an example of British greed. Germany also had lots of anti-Semitic and anti-Slavic posters in order to brainwash the German people into thinking these two groups were genetically inferior to Germans. Allied propaganda showed the Japanese, Germans, and Italians as bent on destroying civilization and ushering in a new dark age. Frank Capra's Why We Fight series comes to mind as a great example of the history that was still being written as the war was fought. Some propaganda on the Allied side, especially American anti-Japanese propaganda, appeals to racism in this country. Propaganda was also used to unite civilians into working longer hours in war industries and rationing food and material for the armies at the front. Even cartoon characters such as Bugs Bunny and Mickey Mouse encouraged both soldiers and civilians alike to buy war bonds in order to defend the world from the Axis powers. Mass media in the 1940's was more readily available than it was during the 1910's, and both sides harnessed it more with the use of posters, cartoons, and movies.