As World War II progressed, Hitler's attention became focused on foreign affairs and the conduct of the war to the exclusion of all else. Hess, not directly engaged in either of these endeavours, became increasingly sidelined from the affairs of the nation and from Hitler's attention; Bormann had successfully supplanted Hess in many of his duties and usurped his position at Hitler's side. Hess was concerned that Germany would face a war on two fronts as plans progressed for Operation Barbarossa, the invasion of the Soviet Union scheduled to take place later that year. He flew solo to Britain on 10 May 1941 to seek peace negotiations with the British government. He was arrested on arrival and spent the rest of the war as a British prisoner, eventually receiving a life sentence for war crimes at the Nuremberg trials in 1946. Speer later said Hitler described Hess' departure as one of the worst blows of his life, as he considered it a personal betrayal. Hitler ordered Hess to be shot should he return to Germany and abolished the post of Deputy Führer on 12 May 1941, assigning Hess' former duties to Bormann, with the title of Head of the "Parteikanzlei" (Party Chancellery). In this position he was responsible for all Nazi Party appointments, and was answerable only to Hitler. By a Führer decree ("Führererlass") on 29 May, Bormann also succeeded Hess on the six-member Council of Ministers for Defense of the Reich, which operated as a war cabinet. He simultaneously was awarded cabinet rank equivalent to a "Reichsminister" without portfolio. Associates began to refer to him as the "Brown Eminence", although never to his face.