The first uprising against Portuguese rule in Africa occurred in Angola in March 1961, when primitively armed Bakongo tribal nationalists in the extreme north of the province attacked several coffee plantations, massacring white Portuguese owners and their families, as well as black African workers who refused to cooperate. Bloody retribution followed at the hands of local whites and blacks who had suffered at the hands of the insurgents. The revenge killings abated only in May 1961, when 10,000 troops arrived to reinforce the 6,000 white soldiers and a similar number of locally conscripted Africans already in Angola. Under the leadership of Holden Roberto, the insurgents found sanctuary across Angola's northern and northeastern borders in the Democratic Republic of the Congo (present-day Zaire). Roberto's group eventually became the National Front for the Liberation of Angola (Frente Nacional de Libertação de Angola-- FNLA), one of the three major anti-Portuguese guerrilla forces. Portuguese units, relying heavily on aerial bombardment and strafing attacks, managed to stabilize the military situation in the north. They brought large segments of the population into aldeamentos (controlled villages), similar to the strategic hamlets used during the Vietnam conflict.

While the intermittent warfare dragged on into the mid-1960s, as many as 70,000 troops (40,000 of them European) were involved in the Angolan conflict. By 1966, two rival insurgent groups gradually superseded the FNLA. One was the Popular Movement for the Liberation of Angola (Movimento Popular de Libertação de Angola--MPLA), a communist-oriented group supported militarily by the Soviet Union and other communist countries. The other was the National Union for the Total Independence of Angola (União Nacional para a Independência Total de Angola--UNITA), based among the Ovimbundu in the south.

From the mid-1960s until the April 1974 coup, Portuguese government forces were generally in control. Insurgency continued, however, as long as the guerrilla movements could obtain sanctuary in neighboring states. The long years of conflict increasingly damaged the morale of both the military and a large segment of the Portuguese people. A few months after the revolutionary government came to power in Lisbon in 1974, it began negotiations with the Angolan factions. Full independence was granted on November 11, 1975. Portugal officially announced its losses in Angola as 1,526 killed in action and 1,465 noncombat deaths. Other sources estimated a much higher mortality figure.

Data as of January 1993