War has always led to prisoners. In ancient times, many were turned into slaves by the victorious armies, while in medieval Europe, they were often returned to their families in return for a ransom, leading to fortune or poverty depending upon which side one was on. By the Napoleonic era, as armies grew in size and professionalism, many were kept in camps for the duration of the fighting, their captors not wanting to restore their enemies' manpower while the fate of nations hung in the balance.

In the first half of the 20th century, war was fought on a global and industrial scale. Millions of men were flung into the grinder of World War I and World War II, leading to commensurately huge numbers of prisoners of war (POWs). Camps were built to hold thousands of captives, with their own barracks blocks, parade grounds, and even farms. In World War I, there were several fronts in the war—Britain, France, Belgium, and Germany faced each other on the Western Front, fought mostly in northeast France and Belgium, while Germany and Austria Hungary faced Russia on the Eastern Front, where much of the war was fought in East Prussia and what is now Poland. The Italians and Austrians fought in the region of northeast Italy, and the Austrians and Bulgarians faced Serbia and then later an Allied army based in Salonica in the Balkans. The Ottomans faced Russia in northeast Anatolia, the British and Allied forces in the Mesopotamian campaign (mainly in today’s Iraq), the British in Palestine, and the Allies at Gallipoli.

During the 20th century's two major global wars, prisoners were taken across the world, and prisoners of war were typically comprised of two classes: officers and other ranks. Officers were often treated well, as there was still a sort of aristocratic courtesy among officers, particularly among the Germans, British, French, and somewhat less so for the Russians, Italians, and Turks.