Map of the Angolan Civil War during September 1981 - January 1984.
Finding success in Cuando Cubango province, UNITA expanded their operations into Moxico by the end of 1981. The following two years saw UNITA gradually expanding their territorial control while also intensifying their guerrilla campaign in the country's interior. A major escalation of the war happened at Cangamba where UNITA attacks, paired with South African air support, managed to force the besieged government and Cuban garrison to withdraw. This event, along with South Africa's next cross-border offensive, Operation Askari, would bring Angola into the forefront of the Cold War.
Sources used:

Adrien Fontanellaz's and Tom Cooper's "War of Intervention in Angola: Volume 2 - Angolan and Cuban Forces at War, 1976-1983"
Adrien Fontanellaz's and Tom Cooper's "War of Intervention in Angola: Volume 3 - Angolan and Cuban Air Forces, 1975-1985"
John Turner's "Continent Ablaze: The Insurgency Wars in Africa 1960 to the Present"
Stephen Weigert's "Angola: A Modern Military History, 1961-2002"
Own work
Rr016