Five Prisoners of War standing in an underground POW camp, Fort XV in Poland, 1941-1944. The camp held approximately 1000 prisoners, housed in 30 rooms. The kitchen was where Red Cross parcels were prepared on one stove for 1000 men. Details from verso. Fort XV was one of a number of defensive forts situated around the city of Thorn, Poland. Forts 11 to 17 were converted to hold prisoners and collectively known as Stalag 312. Fort XV held French POWs.