<P> The German reunification (German: Deutsche Wiedervereinigung) was the process in 1990 in which the German Democratic Republic (GDR / DDR / East Germany) joined the Federal Republic of Germany (FRG / West Germany) to form the reunited nation of Germany, and when Berlin reunited into a single city, as provided by its then Grundgesetz constitution Article 23 . The end of the unification process is officially referred to as German unity (German: Deutsche Einheit), celebrated on 3 October (German Unity Day) (German: Tag der deutschen Einheit). Following German reunification, Berlin was once again designated as the capital of united Germany . </P> <P> The East German regime started to falter in May 1989, when the removal of Hungary's border fence with Austria opened a hole in the Iron Curtain . It caused an exodus of thousands of East Germans fleeing to West Germany and Austria via Hungary . The Peaceful Revolution, a series of protests by East Germans, led to the GDR's first free elections on 18 March 1990, and to the negotiations between the GDR and FRG that culminated in a Unification Treaty . Other negotiations between the GDR and FRG and the four occupying powers produced the so - called "Two Plus Four Treaty" (Treaty on the Final Settlement with Respect to Germany) granting full sovereignty to a unified German state, whose two parts were previously bound by a number of limitations stemming from their post-World War II status as occupied regions . </P>

When did east germany and west germany unite