The End of the Soviet Union
This attempt ended in failure just two days later. However, it managed to destabilize what was left of the Soviet Union. By December that year, the Soviet Union was destroyed.
Source: businessinsider.com
Unfortunately, it led to putting the Soviet space program and Mir space station in question. This was because the spacecraft bound of Mir was launched from the Baikonur Kazakhstan base, one of the republics fighting for independence.