Long-term nationalist tensions and imperialistic rivalries in Europe contributed to the outbreak of World War 1. Germany had a strategic plan to defeat France first through a rapid attack, then focus on Russia with a two-front war. The assassination of Archduke Franz Ferdinand sparked a series of diplomatic failures, military mobilizations, and declarations that led countries into the war. New technologies like tanks, air power, chemical weapons, and submarines transformed the brutal trench warfare on the Western and Eastern Fronts, as all sides suffered millions of casualties over four years of conflict.
