The beginning of World War I was sparked by political, economic and territorial conflicts among the great European powers. Militarism, a sophisticated web of group of alliances, nationalism and imperialism also led to the outbreak of the World War I.
The major cause of World War I was the diplomatic collision among the European great powers, including France, Italy, Britain, Germany, Russia and Austria-Hungary, over European and colonial considerations, leading to tension build-up. However, the immediate cause of crisis was tension over territory in the Balkans.
This started with the competition among Russia, Serbia and Austria-Hungary for control of the territory and dominance in the region. The tension also attracted the attention of the rest of the Great powers, who ended up in the conflict through various alliances and treaties. Similarly, the growth of nationalism in Europe and underlying territorial disputes contributed immensely to the crisis.
Other causes include a sophisticated system of alliances and the seeming breakdown of the power balance in Europe. At the same time, rivalry for wealth, power and prestige took the center stage, with each of the great powers aiming to dominate. Economic and military rivalry in industry and trade also played a significant role, with each side attempting to muzzle the other.