In WW II camps, supply of various goods was fixed by external conditions: rations, etc. But after receiving the rations, the prisoners began exchanging what they didn’t want for what they particularly needed. Soon there was an elaborate price system for every product in terms of cigarettes (which evolved as the money commodity). Prices in terms of cigarettes fluctuated in accordance with changing supply and demand.
As mentioned in Quality of Money cigarettes were the most “moneylike” products available in the camps. They were in high demand for their own sake, they were divisible, portable, and in high value per unit weight. They were not very durable but they could make do in the few years of the camps’ existence.