During World War II, Germany had a huge shortage of coffee because Germany was cut off from its resources. Real coffee was very rare and was only available on the black market.
People and soldiers therefore drank Ersatzkaffee, commonly known as "Muckefuck" (from the French "Mocca faux" = false coffee). This coffee is made from roasted chicory roots, malt, barley, rye, acorns and other things that have been available. This type of coffee contained no caffeine and had a bad taste.
In the camp or in a personal grinder, soldiers could grind coffee beans and prepare a cup of coffee. They could also grind their coffee ration in a camp grinder.