Final answer:
Propaganda posters were used during World War I and World War II to influence America's behavior and garner support for the war effort.
Step-by-step explanation:
Propaganda posters were used during World War I and World War II to influence America's behavior and garner support for the war effort. These posters showcased the subject of the war, such as infantrymen, the moral struggle, or the need to purchase war bonds, and employed various techniques to promote patriotism and a sense of duty. By using powerful visuals, emotional appeals, and persuasive messaging, the posters aimed to encourage civilians to show support for the war by enlisting in the military, working in factories, rationing food, or purchasing war bonds. However, it is important to note that these posters often presented a selective and idealized view of the war, lacking a realistic assessment of its intricacies and challenges.