In June 1941, according to Höss's trial testimony, he was summoned to Berlin for a meeting with Himmler "to receive personal orders". Himmler told Höss that Hitler had given the order for the "Final solution". According to Höss, Himmler had selected Auschwitz for the extermination of Europe's Jews "on account of its easy access by rail and also because the extensive site offered space for measures ensuring isolation". Himmler described the project as a "secret Reich matter" and told Höss not to speak about it with "SS-Gruppenführer" Richard Glücks, head of the Nazi camp system run by the Death's Head Unit. Höss said that "no one was allowed to speak about these matters with any person and that everyone promised upon his life to keep the utmost secrecy". He told his wife about the camp's purpose only at the end of 1942, since she already knew about it from Fritz Bracht. Himmler told Höss that he would be receiving all operational orders from Adolf Eichmann, who arrived at the camp four weeks later.