The correct answer is "Coup d' Etat."
In some African nations, the end of European colonial rule brought about political instability. Many countries were not able to establish a stable democratic government. As a result, some nations were vulnerable to, which can be defined as sudden, violent overthrows of governments or "Coup d' Etat."
Coup d' Etat is the term to identify the sudden, violent overthrow of a government, basically by the military. When this happens, the Army of the nation takes total control of the country, the Armed Forces, and the Police. This change is made at the top of the hierarchy of the government and the leader is immediately replaced by another civilian or a military man. After this, the interim leader can organize new elections or stay in power during a undeterminated time.