No effective national government existed in Germany following the surrender of the German High Command in May 1945; all national military and civil authority and powers were therefore exercised by the four Allied Powers. The Allies then maintained that as the former German Reich no longer existed in fact; so, as the 'highest authority' for Germany, they were entitled to assume all sovereign powers without limitation of scope or duration and could legitimately impose whatever measures on the German people within German national territory as any government could legally do on its own people—including validly ceding parts of that territory and people to another country. They argued furthermore that international conventions constraining occupying powers in wartime from enforcing fundamental changes of governmental system, economic system or social institutions within the territory under their control—the Hague Regulations of Land Warfare and the Geneva Conventions—did not apply; and could not apply, as the termination of Nazi Germany and the total Denazification of German institutions and legal structures had been agreed by the Allied Powers as absolute moral imperatives.[3] Consequently, the Potsdam Agreement envisaged that an eventual self-governing state would emerge from the wreckage of WWII covering 'Germany as a whole', reuniting Berlin and the four Allied control zones; but that this state would derive its sovereignty solely from that then being assumed by the Allied Powers, and its constitution would require the approval of all the Allies through the Council of Foreign Ministers.