Many African nations demanded that colonial governments grant them their independence.
European nations had established colonial empires in Africa in the late 19th and early 20th century. Coming out of World War II, those European nations lacked the resources and energy to maintain far-away empires in Africa and Asia -- as well as the ability to suppress independence movements that broke out in those regions after the Second World War.
Another factor was that coming out of the period of the World Wars, there was a prevailing attitude among Western governments that people should be allowed self-determination of their own nations and governments. In other words, there were pressures to abandon colonialism and imperialism, believing all nations should be able to determine their own destinies. Coupled with that were rising nationalistic attitudes in African nations that had been dominated by European imperialism, which sparked the rise of national independence movements in Africa.
