Since the early starts of humanity there's been a need of communicating through visual language. Throughout history diverse media have used these graphic resources in their favour as a way to alienate people. Propaganda is fundamental for the imposition of ideologies and one clear example of this, are the propaganda campaigns that different versions of fascism used at the time in Europe as well as the american counterpart.
As graphic designers we can take some clues on the fundamentals of these campaigns (overlooking the ideologies behind them) and how they used graphic elements to project powerful messages. Their principal aim is to create an emotional impact on the spectators and to portray whatever message they want to get across. And what better way to do that than taking advantage of equally powerful images that are carefully constructed for that purpose. There's a lot of illustrations that either idealize or try to create shocking images for attention- all of this paired up with straightforward messages in bold type.
Just like today, every country has their own visual codes and applied them accordingly for their propaganda. We can see that nazi propaganda is way more forward than the american war campaigns, whereas the latter appeals more to a shock impression looking for emotional response and imposing fear as a medium of control.
In other cases the propaganda was focused on the earlier stages of the imposing of ideologies, as in the case of the fascist movement in Croatia. There were books that were intended for children, basically teaching by illustrations the basis of their fundamentalism. These particular illustrations are covers of a magazine that was intended for children and made by the croatian fascist movement called Ustaša, and they were meant to make their ideology part of quotidian life... targeting children first.
And as a last example of the stylistic differences between every country, here are some chinese posters that were used for the communist uprise. The graphic elements used are different from the western campaigns, basically sticking to their own graphic identity: the use of flat perspective, the overuse of colour red and the omnipotent image of the movement's leader. This is actually a good reminder of how powerful images are and what an impact graphic design work can have in specific contexts. We can actually see the same principles applied everyday now in advertising and how it really shapes how people see things, either for better or worse.