Assimilation is a process in which the people take in and start to fully understand information or ideas.
Progressives are people that advocate for a social reform because of displeasure by the ones that are in place.
Social Darwinism is a theory that suggests that all peoples, individuals, and groups are subject to the exact same Darwinian laws of natural selection as all animals and plants in the nature.
Unrestricted submarine warfare is a type of warfare in which the submarines are sinking vessels without giving them any warning.
League of Nations is the organization that was the predecessor of the United Nations, being formed after the World War I with the treaty of Versailles.