The assassination of Austrian Archduke Franz Ferdinand in 1914 triggered long-simmering tensions between European countries into full-scale world war. Immediately, two major military alliances were forged; Germany and Austria-Hungary signed an agreement to support each other in a European war; Russia and France reached an arrangement of their own. No country wanted to be left without allies, so each nation spent a great deal of money and energy arming itself for war.

All these developments, along with the deep underlying trends that we have covered in this course, made war seem inevitable. Everyone thought that the new technologies of industrialization would make war quick and decisive. The railroads could quickly transport large numbers of troops and equipment, and once a country started mobilizing, it would be hard to stop without giving the enemy an advantage.

Imperialism was another factor driving Europe toward war. Countries like Germany and Russia felt they should have control over lands beyond their borders. This created tension between the larger nations and often led to rivalry as each empire sought out more land to own and rule.

Despite all of these factors, some historians argue that better diplomacy could have delayed the outbreak of war. However, others point out that the pace of military developments meant that even the best diplomats could not keep up. For example, the sinking of the passenger ship Lusitania by a German U-boat in 1915 helped turn American public opinion against neutrality.