YOUR COUNTRY NEEDS FLAX, AND WILL PAY WELL FOR IT" poster
The pattern
This still is filed under Demonstration ad.
Define
The product does the arguing. The viewer sees the thing work, not a slogan about the thing working.
Mechanism
Proof by performance. The claim is the action: a visible, testable result the reader can replay.
Verdict
We can show a result in seconds
Why it works
It uses clear, bold typography and a direct visual metaphor to explain why flax is needed (for paint). It immediately follows the patriotic appeal with a strong financial incentive.
Steal this when
You have both a high-minded (patriotic/mission-driven) and a practical (financial) reason for someone to take action; present them back-to-back.