Two rival countries, two kindred souls. While their compatriots fight against each other in the first modern "Great War," Stefan Zweig and Romain Rolland become intimate pen friends. Deeply impressed by Rolland's European stance, Zweig wrote a letter to the French writer in 1910, which would become the starting point of a lifelong dialogue. These remarkable documents provide an intimate glimpse into lived European (intellectual) history and serve as evidence of a generous friendship. Even as the First World War loomed, these two European intellectual giants of the 20th century maintained their exchange, holding onto their shared identity as Europeans. It was only through his engagement with the fifteen years older Romain Rolland that Stefan Zweig matured into the uncompromising pacifist he would remain for the rest of his life.