The First World War represented a tragic crossroads for the international Left. The pressing decision of the hour—whether to collaborate with or to resist imperialist war—was answered overwhelmingly with the former choice by almost every major party of the Second International. Here is the story of those who chose the second road; a road that, the author argues, renewed socialism after the cataclysm of war. R. Craig Nation has been a professor of strategy and director of Eurasian studies at the US Army War College in Carlisle, Pennsylvania, since 1996. He is a specialist in war and peace studies.