The first countries involved in the First World War were Serbia and Austria-Hungary. The event that led to the outbreak of the conflict was the assassination of Archduke Austrian Franz Ferdinand. After that, the Austro-Hungarian government had been negotiating for a long time about what kind of response to take regarding Serbia. In addition, the Austrian side was worried about the expansion of Serbian territory during the period 1912-1913. as a result of the Balkan wars, as well as the threat that came from the southern Slavs. Another moment haunted them: whether Russia would take the side of Serbia. To prevent this, it was necessary to enlist the support of Germany. For the latter, Austria-Hungary was the only possible ally, therefore, in no case could it be left in a difficult situation.
In 1913, Russia was not able to support Serbia, which needed its help to maintain the situation on the Adriatic, and in 1914, without substituting the expected shoulder, Russia risked weakening its influence in the Balkans.
The causes and nature of World War I lay in a tense international situation. Germany understood that war could not be avoided. Only the dates were unknown. After all, it is necessary to choose the right moment until rearmament has taken place in Russia, military reorganization in France, and a profitable maritime treaty between Britain and Russia has not been signed. Therefore, the German side could regard the outbreak of hostilities as the only way to achieve world domination.
The reason for the First World War was also in the arms race, in which all the major powers were involved. Not a single state was frightened by the military power of others, so this fact cannot be considered as a deterrent. Countries sought to expand their own production of weapons and did not tremble before the military program of opponents. It would seem that Britain should have retreated before the power of the German fleet, but she wished to strengthen her influence and gain naval superiority at all costs.
Therefore, by 1914, the causes of the First World War were very serious; they set the world community on the realization that military operations could not be avoided. France as a result of the war of 1870 remained dissatisfied with the loss of the territories of Alsace and Lorraine, while Germany, on the contrary, was satisfied with its position, feeling military superiority over other European states. In addition, the end of the 19th century was marked by an understanding of the need for national independence in a number of countries, which jeopardized the continued existence of the Ottoman and Habsburg empires and, as a result, led to instability in the international system.
The causes of the First World War, according to the followers of Marxist theory, were in the antagonistic mood between the Prussian junker and the Russian landowner. A rather long list of other premises was added to them: the struggle for iron and coal, communication lines, spheres of influence, colonies, national contradictions. No less role was played by the role of personality in history. For example, French President Henri Poincaré spent his childhood in Lorraine, which was occupied by the Germans. This fact also could not but affect future historical events.
The causes of the First World War are also hidden in the following moments. During the reign of Nicholas II, Russia encountered difficulties moving cargo through the Bosporus and Dardanelles, as a result of which it suffered significant economic damage. She really needed a free exit and entrance from the Black Sea, since the main grain export passed through Constantinople. By 1904, an alliance was created between Russia and France under the name of the Entente. A few years later, Russia signed an agreement with England on the delimitation of spheres of influence in countries such as Afghanistan, Persia and Tibet. Despite reaching an agreement, the Entente in the period of 1907 could not be considered a military bloc, which could not be said about the Triple Alliance. The Entente acquired this status only in 1914 from the moment of signing the tripartite agreement between Russia, England and France on the renunciation of the obligation to conclude a separate peace with opponents.
These were the main reasons for the First World War, which began on July 28, 1914.