In the late 19th century, European powers competed to seize colonies and overseas markets. As Germany grew rapidly, competition with Britain and France intensified. The powers strengthened their military forces and engaged in a massive arms race. Germany and Britain, in particular, competed fiercely over naval expansion. European nations formed military alliances to keep each other in check. Germany, Austria-Hungary, and Italy formed the Triple Alliance. Britain, France, and Russia built the Triple Entente in response. As a result, Europe was divided into two massive spheres of influence. France sought to reclaim Alsace-Lorraine, lost in the Franco-Prussian War of 1871. Germany aimed to isolate France and expand its influence in Europe. Russia sought to expand its influence by supporting Slavic peoples in the Balkans. Austria-Hungary was wary of Serbia's growing power in the Balkans. In Serbia, nationalism aimed at unifying South Slavic peoples grew strong. This nationalism clashed with the Austro-Hungarian Empire. The Balkan Peninsula became the 'powder keg of Europe' as the interests of various ethnic groups and powers intertwined. On June 28, 1914, Archduke Franz Ferdinand of Austria was assassinated in Sarajevo. Austria-Hungary viewed Serbia as the mastermind behind the assassination and responded aggressively. The crisis began when Austria-Hungary declared war on Serbia. Russia, Germany, France, and Britain entered the war one after another according to their alliance obligations. Ultimately, the combination of nationalism, imperialism, the arms race, the alliance system, and the Sarajevo assassination expanded into World War I.

The Entente Powers

The Central Powers