From the conclusion of the US Civil War in 1865 to the beginning of the Great War (1914–1918), the world became a more interdependent and interconnected place. The expanding use of technologies such as steamships, railroads, electricity, and telegraph lines created a growing interconnectedness between modern nation states. These nations’ militaries exploited improvements in weapons technology to build “imperial systems” across the planet in the name of “progress” or “civilization.” Fueled by increasingly racist and nationalistic ideologies, European policymakers built huge standing armies and formed alliances with each other to protect the “balance of power” on the continent and secure their colonial possessions. While the growing interconnectedness of the world often fueled the militaristic competition of governments, it also became a “golden age” of internationalism that gave rise to new forms of global cooperation in areas as diverse as communications, finance, commerce, law, and weights and measures. As part of this process, an international movement for peace developed that reflected the efforts of industrialists, social reformers, writers, peace activists, lawyers, working class figures, and political leaders to create a humane and safer world. 1