In the interests of historical accuracy, I should note that the Second Boer War and the Philippine "Insurrection" covered almost exactly the same period of time, 1899-1902 (the war in the Philippines began in February, that in the Transvaal in October, but they ended 5 days apart). There is some question in both cases as to when the camps opened, and when they transitioned from places to keep civilians out of the line of fire to breeding grounds for disease. The credit for the first "modern" use of such facilities probably goes to the US for the internment of Indian families on reservations so their men would quit fighting, in the 1880 and early 1890s. (Earlier reservations were established for different reasons) A close runner-up (chronologically) would be the similar treatment given to the families of rubber workers in the Belgian Congo.