Always a good subject. Alright, we'll go over political cartoons, propaganda posters and mocking cards/postcards (a somewhat unknown form of propaganda that is really interesting).
Propaganda Posters were the most prevalent in the First World War. Propaganda posters were a type of art-based propaganda that were used primarily for purposes of recruitment and for gaining internal civilian support. One of the most popular examples is the: destroy this mad brute. enlist" poster which depicts a beast (most likely a gorilla or something of that nature) holding a bat and a damsel in distress.
Mocking cards/postcards are small playing cards or postcards which were made with the primary purpose of belittling the enemy or bettering the image of the nation and its allies. My favorite one is the "either way you look at it it is a pig" card which mocked German soldiers.
Cartoons are propaganda but often made by the public. Political cartoons serve to demonstrate a particular opinion on a subject often controversial or relevant to politics. One example would be the "don't let them carve those faces on our mountain" cartoon by Dr. Seuss (aka the best political cartoon artist).