Prisoners of war and civilian "undesirables" were brought in from occupied territories. Millions of Jews, Slavs and other conquered peoples were used as slave labourers by German corporations, such as Thyssen, Krupp, IG Farben, Bosch, Daimler-Benz, Demag, Henschel, Junkers, Messerschmitt, Siemens, and even Volkswagen,[9] not to mention the German subsidiaries of foreign firms, such as Fordwerke (a subsidiary of the Ford Motor Company) and Adam Opel AG (a subsidiary of General Motors) among others.[10] Once the war had begun, the foreign subsidiaries were seized and nationalized by the Nazi-controlled German state, and work conditions there deteriorated as they did throughout German industry. About 12 million forced labourers, most of whom were Eastern Europeans, were employed in the German war economy inside Nazi Germany throughout the war.[11] The German need for slave labour grew to the point that even children were kidnapped to work in an operation called the Heu-Aktion.