[Publius6961]

Propaganda was created to convince American populace that Germany needed to be conqered.

This is an odd way to phrase things.

Propaganda it might have been. Or not. In any case I cannot see the word "conquered" being appropriate here. "defeated," perhaps.
Is English your first language?

[freepguy]

QUE? NO HABLA ENGLES CABRON.

[jonascord]

The American Army, under Pershing, was convinced that the only way to confirm that Germany would no longer be a threat to peace would be to actually invade the country, and hammer the German Army to bits, forcing it to surrender. American officers were still planning attacks at 10:45 on Armistice Day. The phrase "Conquer the Peace," was popular.

The British and French armies were shattered, however, and simply didn't have the will or the manpower to invade. The German Army, instead, simply got on trains and went home. Hence the 'Stab in the Back' meme that Hitler used within two years in Munich.