Why did the European alliance system develop before World War I?

European
alliance systems formed as nations began to fear attacks from one another. The formation of
Germany and its successful war against France was a major catalyst in this fear. Another
catalyst was the extreme nationalism of the period, especially the nationalism felt in the
Balkans as the Ottoman Empire disintegrated and new nations formed. Germany sought to isolate
France and it would form alliances with Austria-Hungary and Italy. France united with Russia in
order to pressure Germany. Russia supported Slavic nationalism in the Balkans, and
Austria-Hungary would view this as a threat by 1914. By 1907, Britain would join the Entente due
to a resentment of German naval buildup. The new sets of allies pressured one another through
loans and promises of assistance in order to promote military spending and taking a hard line
against the alliance's enemies. As 1914 approached, many of the leaders of Europe saw the
alliance system as normal and as a way to prevent war. The two sets of alliances, the Central
Powers and the Entente, promised to support their allies in times of war but most of the
countries traded willingly with countries in the opposing alliance. No one predicted a
full-scale war in the summer of 1914, but it was partially fueled by the alliance
system.