This chapter focuses firstly on the expansion of internment and confinement between 1915 and the beginning of 1917 in Europe and outside it. It traces the differences among the various belligerents in the treatment of enemy aliens, the living conditions in the camps, and the national, gender and generational composition of the inmates. It also concentrates on the one hand on the popular pressure in support of the wholesale internment of enemy aliens and, on the other, on the broadening of the humanitarian activities pursued by international non-governmental organization such as the International Committee of the Red Cross that actively promoted the exchange of prisoners of war and civilian internees. The second part of the chapter addresses the spread of a nationalistic economic discourse that boosted the intensification of the economic war and the attack on enemy aliens' property with the creation of new state bureaucracies and the beginning of the liquidation of sequestered assets. The chapter shows how the capacity of the state to enforce such policies was continuously put to the test by the effect of the war on politics and by its military evolution.