This article examines Jewish religious life and rabbinic leadership in the city of Vilna (Vilnius) during the First World War by focusing on three figures: Rabbi Hayim Ozer Grodzienski, Rabbi Isaac Rubinstein and Ester Rubinstein (the wife of the latter). Humanitarian and social crisis, together with political change, disrupted religious life in Vilna, leading to a retrenchment of Orthodoxy, as it ceased to be the way of the establishment and became one Jewish movement among many. New schools and new communal institutions were formed, while rabbis reformulated the traditional lay–rabbinic division of labour. While the Rubinsteins used the war to further a religious-Zionist model that made compromises with modernity, Grodzienski favoured a more traditionalist stance. These differences led to a postwar split between religious Zionism and ultra-Orthodoxy.