Short answers, pulled from the story.
The inner German border began as a simple line drawn on a map in Potsdam, Germany, on the 1st of August 1945. This boundary separated the Soviet occupation zone from the Western Allied zones that included British and American territories.
An East German citizen who escaped to the West automatically gained full citizenship rights under West German law. This legal reality created a powerful incentive for millions to flee eastward toward freedom and economic opportunity.
More than eight thousand three hundred civilians living along the line were forcibly resettled in Operation Vermin during this initial phase. Construction of the modern frontier system began in September 1967 with expanded metal barriers replacing simple barbed wire fences.
The largest crossing point was Helmstedt-Marienborn where thirty-four million six hundred thousand travelers passed between 1985 and 1989. This location codenamed Checkpoint Alpha served as the first of three Allied checkpoints leading toward Berlin.
On the 9th of November 1989 the East German government announced the opening of the inner German border during Die Wende. The border was not completely abandoned until the 1st of July 1990 exactly forty-five years after its initial establishment.