There were many immediate and underlying or fundamental causes of World War I. The difference between an underlying and immediate cause is that an underlying cause develops over a long period of time and indirectly leads to a specific event, and an immediate cause is a specific short-term event that directly leads to another event or series of events. While the immediate cause of World War I was the assassination of Francis Ferdinand, the archduke of Austria, by a Serbian member of the Black Hand secret society, there were various basic causes of the war.
Three of them were nationalism, alliances between European powers, and militarism. Nationalism is a devotion and loyalty to one s own nation, with primary emphasis on furthering its interests as opposed to those of other countries. This feeling widely spread throughout Europe during the 19th and 10th centuries and caused many problems. The Slavic people of Bosnia and Herzegovina wanted to break away from Austria-Hungary and unify with other Slavic nations. Russia as a Slavic nation backed up the two countries in this matter, therefore causing tensions between Austria-Hungary and itself.
Nationalism was also a source of anger between France and Germany as France resented its defeat in the Franco-Prussian War (1870-1871). Alliances between European nations can also be considered an underlying cause of World War I. As a result of the Triple Alliance consisting of Germany, Austria-Hungary, and Italy, the Triple Entente (understanding) was formed between France, Britain, and Russia. Although France and Britain were natural enemies, their fear of Germany united them together with Russia. These alliances set the final stage for the beginning of World War I. Each country in each alliance would help each other during warfare.
For example, if Germany attacked France, Britain and Russia would help France, and Italy and Austria would help Germany, dragging Europe into a state of chaos and violence. Militarism was also an underlying cause of World War I. As the alliance system divided Europe into opposing groups, each nation began to increase spending on its military. This set a belligerent mood in Europe as each nation was prepared to fight a war. A German officer once said “in time of peace, prepare for war,” and that is exactly what European nations did, eventually leading to the Great War.
Without a doubt, the one underlying cause of the three described above that was most responsible for World War I was the system of alliances. The Triple Alliance and Triple Entente created extremely high tension in Europe which motivated countries to move into war for an inane incident such as the assassination of the archduke of Austria. Europe was divided into two opposing groups and each nation was ready to enter war due to militarism. The high tensions between European nations ultimately led to the declaration of war on Serbia by Austria on July 28, 1914, marking the beginning of World War I.