detainees.

Nevertheless, this more “civilized” approach toward enemy aliens during the First World War managed to rehabilitate the sullied image of concentration camps. People accepted the notion that a targeted group might turn itself in and be detained during a crisis, with a reasonable expectation to one day be released without permanent harm. Later in the century, this expectation would have tragic consequences.

Yet even as the First World War raged, the camps’ bitter roots survived. The Ottoman government made use of a less-visible system of concentration camps with inadequate food and shelter to deport Armenians into the Syrian desert as part of an orchestrated genocide.

And after the war ended, the evolution of concentration camps took another grim turn. Where internment camps of the First World War had focused onforeigners, the camps that followed—the Soviet Gulag, the Nazi Konzentrationslager—used the same methods on their own citizens.

In the first Cuban camps, fatalities had resulted from neglect. Half a century later, camps would be industrialized using the power of a modern state. The concept of the concentration camp would reach its apotheosis in the death camps of Nazi Germany, where prisoners were reduced not just to a number, but to nothing.

The 20th century made General Martínez Campos into a dark visionary. Refusing to institute concentration camps on Cuba, he had said, “The conditions of hunger and misery in these centers would be incalculable.” And once they were unleashed on the world, concentration camps proved impossible to eradicate.