I am reading Anne Applebaum's Iron Curtain right now. One thing that I'm not sure I understand is how Germany was actually partitioned into East and West. Was it the case that there was a gradual shift towards two different countries on both sides, or was there an official agreement between the Soviet and the British/American/French governments that the country would be partitioned. To what extend did the agreement at the Yalta conference play a role in this? Also, were the Marshall Plan and Berlin Blockade contributing factors, or by that time was the partition already a foregone conclusion?
Thanks for reading, could be totally off-base with some of this, so feel free to correct/enlighten.
The partitioning of Germany was both official and unofficial in a way - Germany was formally partitioned into four occupation zones, but there was the intention that at some future point this would end. The Potsdam Agreement set out the initial terms of the occupation of Germany and the new German-Polish border, but these were only provisional until a final settlement "to be accepted by the Government of Germany when a government adequate for the purpose is established" (Article I (3)(i), http://avalon.law.yale.edu/20th_century/decade17.asp). However growing tensions meant that the administration processes and procedures that were supposed to work broke down, and decisions made to encourage favourable German administrations in each part.
The emergence of West and East Germany was more 'unofficial' - it was the result of disputes between the Western Allies and Soviets and each and there was never an official agreement as such that there would be an ostensible Western Allied client West Germany and a Soviet client East Germany. The two German republics did not initially recognise the other and claimed to be the only legitimate German state, nor did the Western Allies/Soviets initially recognise the Germany that wasn't "theirs".
As an aside, modern Germany in fact remains the Federal Republic of Germany established in 1949, because in 1990 the GDR voted to dissolve itself as a state and join the Federal Republic, rather than a legally new state being formed from both republics, and the occupation of Germany as set out at Potsdam only legally ended in 1990 with the Treaty on the Final Settlement with Respect to Germany