Of the four MAIN. underlying causes of the First World War, nationalism was the most potent because A. European governments felt that if they had the support of their people behind them, they could engage in warfare without risking revolution (which didn't pan out so well for the Russians).

B. European powers wanted raw materials and esources, so their colonies became heavily engaged in industrial manufacturing and distribution

C. it lent to the British wanting to protect their overseas empire, leading them to build up their armed forces and take the Tht to the enemy

D. it's what fueled the Serbians hatred of their Austro-Hungarian rulers, which eventually culminated in the assassination of the Austrian Archduke Franz Ferdinand.​