Causes of war

Nationalism and Self-determination

The principle of nationalism, where peoples with common linguistic, cultural or historical ties seek their own independent nation-state, has been a common cause of warfare throughout history.
The idea of self-determination, the right of a people to determine their own destiny, has often been associated with nationalism, fuelling separatist movements and wars of independence.

Territorial Disputes

Disputes over territory have often sparked wars, and these can range from conflicts over a specific parcel of land, to broader contestations about national boundaries.
Territorial disputes are often closely linked with resource competition, particularly when the territory in question contains valuable resources.

Religion and Ideology

Throughout history, conflicts between different religious and ideological groups have frequently led to wars.
Notable examples include the Crusades, the Thirty Years’ War in Europe, and the ongoing conflicts in the Middle East.

Economics and Resource Scarcity

Economic factors, particularly competition for resources, have often been at the heart of wars.
These can involve direct contests for control of resources (e.g. oil), or could also involve wider economic dynamics such as trade imbalances and economic rivalries.

Political and Power Struggles

Differences in political systems or changes in power structures can also lead to war.
Examples range from revolutions and civil wars sparked by challenges to existing regimes, to wars between nations with differing political ideologies (e.g. democracy vs. communism).

Technology

The development of new militaristic technology can act as a facilitator of war.
This has been particularly apparent in the modern era, where advanced weaponry and military technologies have amplified conflicts and in some cases enabled the initiation of war.

Role of Individuals

The role of individuals, particularly political leaders and military figures were influential in making decisions that lead to warfare.
These include major figures like Napoleon Bonaparte or Adolf Hitler, whose personal ambitions and ideologies helped trigger major wars.

Remember to consider the interplay and overlap between these causes in real-world situations. Rarely does a war have a single cause, and often it is a complex mix of many of these factors that ultimately leads to conflict.