Let me give you the most famous persuasive message that I can quote. Just before the civil war began, the men of the south (in Gone with the Wind) were all fired up about the prospects of war. They all agreed they were going to beat the Yankees in a week. All were fired with energy but one. That one was the most disliked rascal in the room -- Rhett Butler. His comment: "The South will loose. She doesn't produce one cannon." He was trying to say that the south's wealth depended on slavery, not industry. He wasn't a peacenik but later on he provided many reasons against war even though he profited from it.
The point I'm trying to make is that Margret Mitchel (the author of Gone with the Wind) didn't say anything about war itself. She let her character do it. So the first and most important thing you can do is not use any language at all to persuade in fiction. Let your characters do it. Make it plausible for the character to say it, but not a shot in the dark a one time break in the character's personality.
