By 1970, half of the independent countries in Africa had military governments those later transform in authoritarian governance as in Egypt and Libiya (gaddaphi). Instead of elected civilians, the government was controlled by the military or intervened by military in the governance. The factors contributing to the rise of military and authoritarian regimes in Africa are 

1.  African governments inherited a weak political system from the colonial era. Consequently, the first African governments did not have the capacity to govern effectively. Military leaders, thought that they may carry better governance. 

2. African governments were unable to meet the social and economical needs of their citizens in field of job, education, health and services. It disillusioned the citizens and they demanded to overthrow the government. Military saw this situation in favour of themselves to take control over government. 

3. The political environment in early post-colonial years gave rise to ethnic tensions that at times became so severe as to threaten the political system. The military claimed a right to intervene and take power in order to stop ethnic and regional rivalries.

4. The strains on the political system in the early years of independence provided an environment in which corruption was widely prevalent in all African countries. Government officials, often frustrated by their inability to be effective, used their government position to benefit themselves and members of their family. 

5. The African countries are rich from timber, minerals, oil and other raw materials, and needed by industries of developed countries. They became a ground of struggle to the western countries for their vested interests.  Sometimes, developed countries support to the military coup and placed puppet government who favored their interest.

6. Some military leaders used ethnic, religious and sectorial ground to control power and retain it for long period of time by using military for their control. Rivalry and civil wars in African countries after post-independence provided opportunity for authoritarian regimes.

7. The boundaries in Africa were drawn by colonial powers based on their interest avoiding the ethnic, religious and group of the region.  After post independence, African countries started claiming territories of other countries as their own.

This is quite a list of weaknesses in the post-independence governments in Africa. Citizens, who fed up from civilian government, first welcome to military coupe but later realized that military regime was unable to fulfill their demand. Military governments dissolve the legislative government and impose an authoritarian government.