Stalags, according to the Geneva Convention and its predecessor, the Hague Convention, Section IV, Chapter 2, those camps were only for prisoners of war, not civilians. Stalags were operated in both World War I and World War II and intended to be used for non-commissioned personnel (Enlisted ranks in US Army, Other ranks in British Commonwealth forces). Officers were held in separate camps called Oflag. During World War II, the Luftwaffe (German air force) operated Stalag Luft in which flying personnel, both officers and non-commissioned officers were held. The Kriegsmarine (German navy) operated Marlag for Navy personnel and Milag for Merchant Navy personnel.
Civilians who were officially attached to military units, such as war correspondents, were provided the same treatment as military personnel by the Conventions.
The Third Geneva Convention, Section III, Article 49, permits non-commissioned personnel of lower ranks to be used for work in agriculture and industry, but not in any industry producing war material. Further articles of Section III detailed conditions under which they should work, be housed and paid. During World War II these latter provisions were consistently breached, in particular for Russian, Polish, and Yugoslav prisoners. According to the Nazi ideology, Slavic people were regarded as rassisch minderwertig (“racially inferior”).
Prisoners of various nationalities were generally separated from each other by barbed-wire fences subdividing each stalag into sections. Frequently prisoners speaking the same language, for example British Commonwealth soldiers, were permitted to intermingle.
At each stalag the German Army set up sub-camps called Arbeitskommando to hold prisoners in the vicinity of specific work locations, whether factories, coal-mines, quarries, farms or railroad maintenance. These sub-camps sometimes held more than 1,000 prisoners, separated by nationality. The sub-camps were administered by the parent stalag, which maintained personnel records, collected mail, International Red Cross packages and then delivered to the individual Arbeitskommando. Likewise any individuals that were injured in work, or became ill, were returned to the Lazarett (medical care facilities) at the parent stalag.
Stalag Luft III, a large prisoner of war camp near Sagan, Silesia, Germany (now Żagań, Poland), was the site of a spectacular escape attempt (later filmed as The Great Escape). On March 24, 1944, 76 Allied prisoners escaped through a 110 m (approx 360 feet) long tunnel. 73 were recaptured within two weeks. 50 of them were executed by order of Hitler in the Stalag Luft III murders.
The largest German World War II prisoner of war camp was Stalag VII-A at Moosburg, Germany. Over 130,000 Allied soldiers were imprisoned there. It was liberated by the U.S. 14th Armored Division following a short battle with SS soldiers of the 17th SS Panzergrenadier Division on 29 April 1945. Stalag III-C is notable for the escape of US paratrooper Joseph Beyrle, who subsequently joined a Soviet tank battalion commanded by Aleksandra Samusenko, which returned to liberate the camp
Do Svidaniya, Comrades
(I can partially read German so the last two sources required some translation)