Of all the civil wars that have erupted over the past half-century, a large number – but hardly all – involve nationalist movements pursuing greater autonomy. While the sheer number of ethno-nationalist civil wars offers evidence that nationalism can contribute to warfare, many countries with multiple and competing forms of nationalism are not afflicted by civil war and manage nationalist tensions in non-violent ways. Thus, nationalism appears linked to warfare but is neither necessary nor sufficient for it.

This chapter explores factors that help determine whether nationalist movements turn violent. It compares competing nationalist movements in Canada and Sri Lanka and considers why the former has been overwhelmingly peaceful while the latter has suffered a long and devastating civil war. The analysis suggests that nationalism promotes civil war by intensifying grievances and shaping incentives but that these effects depend on contextual factors. Most notably, nationalism has only limited motivational effect in environments with abundant resources and effective and non-discriminatory political institutions. Alternatively, it intensifies the grievances caused by economic scarcity and ineffective and discriminatory political institutions, increases incentives to eliminate nationalist rivals in environments with limited resources and ineffective and discriminatory political institutions, and thereby contributes to nationalist violence.