In Sied Forces, the prisoners of Gross Rosen were forced on what would later be called a death march across the Sudeten mountains. These prisoners were chosen to be moved, rather than executed, because Albert Speer, the German armaments minister, believed the special skills these prisoners had gained at the Phillips factory would be useful in other German factories for the manufacture of "jamming transmitters and equipment for high-performance aircraft". The prisoners were eventually taken to a train station and shipped across Europe to Porta Westfalica in northwestern Germany. Only about 200 of the original 10,000 prisoners, including Kitty and her mother, survived the journey.