During the Crimean War, Crimean Tatars were charged en masse with collaborating with the Allies. At the war's conclusion, nearly 200,000 Tatars left the peninsula to relocate in the Ottoman empire. Mara Kozelsky contributes to an understanding of this critical episode in the Crimean War by examining secret surveillance documents, a collection that records complex state attitudes toward Tatars from the Allied landing on the Crimean coast to the Treaty of Paris. These documents reveal that intelligence operations provided no evidence of a collective Tatar guilt and instead testified to the diversity of pressures on state policies toward subject populations on the front lines of battie. Shifting wartime conditions, religious tensions, and repeated crises at the front highlighted unresolved debates about religion and loyalty to the state. Some officials recommended deporting the Tatars, others encouraged their migration, and still others advocated on the Tatars’ behalf.