This looks like more like a persuasive argument teling people to keep there thoughts and stuff to them selves and not telling the enemy or anyone if they have information about there allies. There were many poster's of thoses back then like " loose lips sink ships". The side that put the poster up wanted to win and having a person saying things about there side could alter the ending effect of the war itself. doesn't really sound like arguing to me but persuasion looks to be what there trying to get at.
