During the last decades of the Austro-Hungarian Empire, Przemyśl, Galicia was the Empire’s largest and most important fortified stronghold. Military spending and construction fueled Przemyśl’s urban growth and a multiethnic community of Poles, Ukrainians, and Jews. During World War I, Przemyśl was completely dominated by the Austro-Hungarian army and the site of the longest siege of the war. At times each of Przemyśl’s ethnic groups was the victim of punitive measures by the Austro-Hungarian or Russian armies, and most of the city’s civilian population was forced to flee at various points during the war. Wartime disruption and the dissolution of the Austro-Hungarian Empire resulted in intense ethnic conflict in Przemyśl. This article shows that as Przemyśl’s military organization was strained to the breaking point, its civil society similarly fractured and eventually turned to national organizations for the security and stability that the Habsburgs could no longer provide.