Himmler's SS (the"Totenkopfverbände") organized and administered Germany’s regime of concentration camps and, after 1941, the holocaust in Poland. The SS, through its Security Service ("Sicherheitsdienst", or SD), hunted down Jews, Gypsies, communists and any persons who the Nazis believed to be either "Untermensch" (sub-human) or against the regime. They were brought to concentration camps. Himmler opened the first of these camps at Dachau on 22 March 1933.