A century ago, an assassin, a Serbian nationalist, killed the heir to the throne of Austria-Hungary as he visited Sarajevo. This act was the catalyst for a massive conflict that lasted four years. More than 65 million soldiers were mobilized by more than 30 nations, with battles taking place around the world. Industrialization brought modern weapons, machinery, and tactics to warfare, vastly increasing the killing power of armies. Battlefield conditions were horrific, typified by the chaotic, cratered hellscape of the Western Front, where soldiers in muddy trenches faced bullets, bombs, gas, bayonet charges, and more. On this 100-year anniversary, I’ve gathered photographs of the Great War from dozens of collections, some digitized for the first time, to try to tell the story of the conflict, those caught up in it, and how much it affected the world. Come back next week for part 2.