Map of the Angolan Civil War during October - December 1975.
After over a decade of fighting, the Portuguese Colonial War came to an end with the Carnation Revolution. With the promise of Angolan independence, the many rebel groups that fought in the war began scrambling for control of the country. The FNLA, supported by the Bakongo people, secured much of the north. The MPLA, supported by the Kimbundu people, secured the capital, Luanda, and most of the coast. And UNITA, supported by the Ovimbundu people, secured the Central Plateau. The fight for Angola intensified the closer the 11 November 1975 independence date approached, eventually triggering multiple foreign interventions.
Sources used:

Edward George's "The Cuban Intervention in Angola 1965-1991 From Che Guevara to Cuito Cuanavale"
Adrien Fontanellaz's and Tom Cooper's "War of Intervention in Angola: Volume 1 - Angolan and Cuban Forces at War, 1975-1976"
Stephen Weigert's "Angola: A Modern Military History, 1961-2002"
Own work
Rr016