The opening of the Iron Curtain between Austria and Hungary at the Pan-European Picnic in August 1989 then triggered a chain reaction, at the end of which there was no longer a GDR and the Eastern Bloc had disintegrated. Otto von Habsburg's idea developed the greatest mass exodus since the construction of the Berlin Wall and it was shown that the USSR and the rulers of the Eastern European satellite states were not ready to keep the Iron Curtain effective. This made their loss of power visible and clear that the GDR no longer received effective support from the other communist Eastern Bloc countries. Thousands of East Germans then tried to reach the West by staging sit-ins at West German diplomatic facilities in other East European capitals, most notably in Prague. The exodus generated demands within East Germany for political change, and mass demonstrations in several cities continued to grow.