As simple as it may sound, the European world collapsed on itself like a matchstick castle in summer 1914. Britain, France, and Russia were bonded in a “Triple Entente,” while Germany, Austria-Hungary, and Italy were bound in a Triple Alliance. These conflicting alliances from previous wars pulled and tugged at the structure until it came tumbling down on June 28, when a Serbian nationalist killed the visiting Archduke Franz Ferdinand, heir apparent to the Austro-Hungarian throne. With nationalist elements threatening to pull its empire apart, Austria-Hungary struck back at Serbia, who then called on its ally Russia for aid. That inspired Germany to declare war on Russia and France, and Great Britain to respond with a declaration of war on Germany. Japan, allied with Britain, followed suit.
At first, the United States declared itself officially neutral, and President Woodrow Wilson counseled his fellow countrymen: “The United States must be neutral in fact as well as in name during these days that try men’s souls. We must be impartial in thought as well as in action, must put a curb upon our sentiments...” Sound and high-minded advice that would be hard for everyone, including Wilson, to follow.
No one could have foreseen the savagery unleashed by the world’s first industrialized war, where the efficiency of modern killing machines surpassed anything imagined in past European conflicts. On the battlefield, 19th-century tactics soon proved useless against 20th-century weapons. Terrorizing the ground, machine guns had a firepower that equaled 80 rifles. Advances in artillery rained down explosives on soldiers in the trenches. Armored cars and tanks first rolled their way into battle in World War I. Chemical warfare, in the form of chlorine, mustard gas, and phosgene, poisoned hundreds of thousands of soldiers.