The Blechhammer (English: sheet metal hammer) area was the location of Nazi Germany chemical plants, prisoner of war (POW) camps, and forced labor camps (German: Arbeitslager Blechhammer; also Nummernbücher). Labor camp prisoners began arriving as early as June 17, 1942, and in July 1944, 400-500 men were transferred from the Terezin family camp to Blechhammer. The mobile “pocket furnace” (German: Taschenofen) crematorium was at Sławięcice.) and Bau und Arbeits Battalion (BAB, English: Construction Battalion) 21 was a mile from the Blechhammer oil plants and was not far from Kattowitz and Breslau. Blechhammer synthetic oil production began April 1[when?] with 4000 prisoners.