During World War One Great Britain incarcerated over 22,000 “enemy aliens” in concentration camps on the Isle of Man. Among these prisoners were many Ottoman citizens who were held in the Knockaloe Camp. Those Ottomans interned reflected the diversity of the empire and included Muslims, Christians, and Jews. Britain is credited as the inventor of the concentration camp, where thousands of civilians would be ‘concentrated’ into a small, ordered area. British officials developed these types of mass detention centers during the Second Boer War (1899-1902) in South Africa and utilized this system of internment to great effect during the Great War. Based upon extensive archival documents from the Ottoman and British National Archives together with memoirs from prisoners, press clippings, circulars, camp flyers, and Red Cross and Red Crescent reports this paper investigates the living conditions, daily life, regimens, social stratifications, recreation, work, and hardships endured by Ottomans incarcerated abroad simply because of their citizenship. It also investigates treatment of prisoners along ethnic, national, and class lines, especially by comparing Ottoman experiences alongside German and Austrian foreign nationals incarcerated in these same camps. Finally, this paper investigates the diplomatic negotiations between governments who are in a state of belligerency regarding their citizens living abroad. These investigations will enable me to categorize treatment and experiences of these prisoners and situate these concentration camps within a broader literature of civilian incarceration during times of war over the course of the long nineteenth century.