how was propaganda used to mobilize populations (both in the home countries and the colonies) for the purpose of waging war.

During World War One, propaganda was employed on a global scale. Unlike previous wars, this was the first total war in which whole nations and not just professional armies were locked in mortal combat. This and subsequent modern wars required propaganda to mobilise hatred against the enemy; to convince the population of the justness of the cause; to enlist the active support and cooperation of neutral countries; and to strengthen the support of allies.