The end of the Cold War.
The end of the Cold War reunited Germany after 45 years of separation. The fall of the Berlin wall changed international relations bringing to the table peaceful negotiations between the German states, the Soviet Union, Western Europe and the United States to unify Germany.
In October 3, 1990, the German Democratic Republic became part of the Federal Republic of Germany, with Berlin reinstated as the capital city. This day is remembered as the German Unity Day.