Final answer:
Nations go to war for various reasons such as gaining or reclaiming territory, extending power, and religious differences, often under the guise of lofty justifications like national interest or ideological imperatives.
Step-by-step explanation:
Nations have gone to war for various reasons throughout history, often driven by a mix of political, economic, and ideological factors. Some primary reasons include gaining territory, to regain territory that was lost or believed rightfully theirs, to extend power over a group or region, or due to religious beliefs and differences. For instance, the concept of irredentism, where a country wants to "reclaim" lost territory for ethnic or historical reasons, was used by leaders such as Hitler in World War II and Putin in the annexation of Crimea.
Moreover, the need to preserve or enhance national strength and autonomy often leads to conflict. This desire for power and influence is illustrated by historical examples like the Viking raids and the French Revolution, as well as modern examples like political strife within a nation or political movements seeking to influence government policy. Fundamentally, wars are frequently justified as necessary to protect or expand a nation's territory, wealth, liberty, or autonomy.