The most brutal and destructive conflict in world history introduced the world to savage trench warfare and lethal new technologies. In addition to 16 million military personnel and civilians killed, it radically reshaped the map of Europe by decimating the sprawling Austro-Hungarian, Ottoman and Russian empires and giving birth to many new nations. It also set the stage for another, far bloodier global conflict two decades later.

The spark that ignited it was the assassination of Archduke Franz Ferdinand in Sarajevo, which triggered a cascade of events that brought the major powers into open conflict. The aspirations of Germany’s leaders to unify all Germans, acquire “living space” (Lebensraum) for agrarian settlers, eliminate Bolshevism and establish the hegemony of an “Aryan”/”Nordic” master race over subhumans like Jews and Slavs added fuel to the fire. Each country had accumulated massive militaries to arm for war, adding to the tensions. Alliances were formed, and soon the dry tinder was ignited.

Unlike in World War II, where the major belligerents were motivated by sharply different ideologies, the nationalism that drove these countries into war in 1914 was more of an irrational competition among empires that were exploitative of their subjects. Even when bloody stalemates became the norm and it was clear that everyone would lose more than they could gain, these nations still persevered, in an irrational effort to prove their virility and power. The result was a horrific conflict with consequences that continue to reverberate today.