The first GDR citizens to show up at the Bornholmer Strasse checkpoint were permitted to leave for West Berlin, although the head of the passport control units had their passports stamped invalid, expatriating the passport holders without their knowledge. As crowds of people continued to arrive, however, this strategy had to be abandoned. Two hours later, the guards “opened the floodgates†and raised the barrier. Over the next hour, around 20,000 people were able to cross the Bösebrücke bridge without being checked. On this night, the peaceful revolution underway in the GDR and the political changes taking place in the countries of Eastern Europe had succeeded in opening the Berlin Wall.