In Europe before 1890 there had been many alliances made mainly by Bismarck, Bismarck organized a system of alliances designed to maintain Germany's hegemony on the European continent. France was determined to challenge the hegemony of Germany because France had been defeated by Germany in 1871 and had been forced to cede two provinces (Alsace-Lorraine) to Germany. Bismarck tried to befriend Austria, Russia, Italy and Britain in order to isolate France. There were many alliances formed in this time but here are the main ones and how they effected the growing tension within Europe:
The Dreikaiserbund of 1872, Bismarck's aim for forming this League was to isolate France by making friends with Austria and Russia. The three countries agreed to maintain the existing territorial arrangements in Europe; (ii) to resist the spread of revolutionary (e.g. socialist) movements; and (iii) to consult one another if any international difficulties arose. France was being diplomatically isolated. But the underlying weakness of this personal understanding between the three emperors was the rivalry between Austria and Russia over the Balkan Peninsula. Both sought to dominate the Balkans. It was difficult for Bismarck to keep them in the same camp. This alliance brewed hatred from France towards Germany. The second Dreikasierbund 1881, Bismarck still wanted to keep Russian friendship after the signing of Dual Alliance (1879) with Austria. The terms of the League were: the Balkans was to be divided into two spheres of influence--the western Balkans (Bosnia and Herzegovina) belonged to Austria and the eastern Balkans (Bulgaria) belonged to Russia; (ii) the three Emperors agreed to consult one another if there was another Balkan crisis, and (iii) the three Emperors agreed to preserve benevolent neutrality if any one of them found himself at war with a fourth power. The League could not last long because Austria and Russia would soon rival over the Balkan Peninsula again. The triple alliance 1882, Bismarck had tactfully encouraged France to expand overseas in the hope of diverting her attention away from Alsace-Lorraine. French annexation of Tunis in northern Africa in 1881 alienated Italy, which was ambitious to build up an Italian empire in Africa. Italy was thus driven into Bismarck's camp in anger. Consequences of this was the emergence of the first alliance camp, a powerful bloc had been formed in central Europe. Germany was now guaranteed against Russia by Austria, and against France by Italy. Bismarck had successfully kept the friendship of both Russia, Austria and Italy and kept France completely isolated. He was indeed a skilful diplomat who was able to handle the European powers for Germany's advantage. Around 1890 there was a change of policy in Germany due to a change in the power this was in the form of Kaiser William the second. Bismarck was a skilful diplomat. For twenty years, he made Germany the centre of the diplomatic stage. France was kept isolated, but Austria, Russia, Italy and Britain were on friendly terms with Germany. Bismarck's alliances were non-aggressive and kept Europe at peace. Yet after 1890, Bismarck fell from power and the new Kaiser took matters into his own hands. Kaiser William II was ambitious, rash and aggressive by nature. Rejecting the idea that Germany was a "satiated state", he wanted to make Germany not only a European power but a world power. He advocated (the drive eastwards into the Balkans and Middle East), colonial expansion and naval expansion. He was also influenced by Pan-German feelings to support Austria's expansionist policy in the Balkans.
When William II came to power in Germany, he thought that sooner or later Germany he allowed the Reinsurance Treaty to lapse. He stressed Germany's political and military ties with Austria. Such a policy, together with the growing Pan-Germanism, aroused strong Russian suspicion. Russia naturally turned to the side of France, which was the irreconcilable enemy of Germany. This alliance between France and Russia was called The dual alliance. The Dual Alliance ended the isolation of France, created a rival alliance to the Triple Alliance, and, most serious of all, faced Germany with the threat of a two front war. But William II failed to sense the danger at the time. He was contented to have Austria as an ally and continued his drive for power and prestige. These alliances in my view were a cause of the first world war for four reasons; firstly, the alliances were made in secret and so produced much distrust and suspicion among the European powers. Their general suspicion prevented their diplomats to devise a suitable solution to many of the crises preceding the war. Secondly, the alliances were always made on a war-footing and so heightened the war tension and led to an arms race among the European powers. Thirdly, since the European powers had made alliances with one another, a small dispute concerning one power might lead to a war involving all powers. Fourthly, the alliances were originally strictly defensive.
In my view another seed that developed tension within Europe was the arousal of militarism. Militarism denoted a rise in military expenditure, an increase in military and naval forces, more influence of the military men upon the policies of the civilian government, and a preference for force as a solution to problems. Militarism was one of the main causes of the First World War. After 1871, the war atmosphere engendered by the secret alliances led to an armaments race among the powers. There was a significant rise in the army and naval estimates of the European powers in this time. An example of this is the naval race between Germany and Britain.
Another minor cause of the First World War was economic rivalries. Undoubtedly economic rivalries played a considerable part in creating international tensions in the years before the First World War. As a matter of fact, the economic rivalries have been much exaggerated. The commercial rivalry between Germany and Russia in the Balkans was not keen, for Russia was not yet a fully industrialized nation with a surplus of products to be sold abroad. The trade rivalry between Britain and Germany had also eased off in the ten years before the war because they developed their markets in different parts of the world -- Britain within her own Empire, and Germany on the continent of Europe. Thus economic rivalries played a minor part in causing the First World War.
One other minor factor, which led to growing tension, was colonial rivalries. After 1870, the European nations began to acquire colonies in Asia, Africa and the Pacific. Their imperialistic activities accelerated from 1880 onwards. Colonial rivalries were a cause of the First World War for two main reasons; firstly, colonial rivalries led to strained relations among the European powers. In Africa, all the European powers except Austria and Russia had colonies there. Thus there were many clashes among France, Britain, Germany and Italy. Secondly, colonial rivalry led to indirectly to the formation and strengthening of alliances and ententes.
So when all these smaller rivalries, alliances and other European matters are put together they put together a complicated yet understandable web of reasons why that in 1890 Europe was an area of growing tension, sowing the seeds of its own destruction, which in 1914 was proven with the outbreak of the First World War which had seemed inevitable for forty years previous to it!