Final answer:
The main message of World War I propaganda was to mobilize the population and gain their support for the war.
Step-by-step explanation:
The main message that the creator is attempting to convey in the World War I propaganda piece can vary depending on the specific poster being analyzed. Propaganda posters during World War I were used to promote patriotism, recruit soldiers, encourage support for the war effort, and shape public opinion. Some posters emphasized the importance of national unity, while others focused on the moral righteousness of the war or the need to financially support the war through the purchase of war bonds. Overall, the primary goal of World War I propaganda was to mobilize the population and gain their support for the war.