What Political Alliances Set Europe Up For World War One?

A series of alliances had lined up the nations into two rival power groups. France had suffered defeat in the Franco-Prussian war that ended in 1871. Germany initiated some of these alliances so as to isolate France and prevent her from taking revenge. First came a dual alliance with Austria-Hungary, followed by a triple alliance to include Italy. These, coupled with an agreement with Russia, seemed to leave France alone, helpless. Though largely secret as to terms, it was well known that these treaties provided for mutual assistance in event of war.
The accession of new leaders in Germany also swiftly changed the picture. William II was now emperor and Bismarck was dropped as chancellor. The new emperor failed to keep up friendship with Russia and alarmed Great Britain by his "saber rattling." His program of naval expansion and demand for "a place in the sun" forced England to reassess her long-standing rivalry with France. Developments in the Far East, notably the Russo-Japanese war, had meantime softened British ill-feeling toward Russia. Thus the second power group took form—Russia, France, Great Britain.
So, in 1914, the powers of Europe were balanced off, three against three. Many felt that such a balance of power was the strongest assurance of peace. The events were to prove them wrong.