I am a big fan of the old propaganda poster. I have been able to get a varied collection over time of posters from around the globe from both the first and second world wars. It's interesting to see not only the evolution of artistic style that a government adapts to their purpose but also the style of the message.
Here are some examples:
These first two are US from the first world war.
Quite dramatic in style. Very Norman Rockwell and almost operatic in scale of imagery. Subject matter wise they are really going for the heart.
Next two are US again but from WW2
Notice the very industrial style? No more opera for these folks! Harsh and to the point. No half clad damsels leading you to war here.
More recently the poster art has become more of a grade school style of drawing with little to no artistic merit yet the messege portion still seems to scream out load and clear.