On 03 October, Germany celebrates the "Day of German Unity".
Already on 09 November 1989, the Berlin Wall fell due to a peaceful revolution. Germany was divided (after the end of World War 2) by a 1400 km long border, the wall ran through the middle of Berlin.
After the wall fell, Germany was officially reunited on 03 October 1990. The 5 states of the GDR, plus the GDR half of Berlin were added back to the Federal Republic of Germany.