The Baixa de Cassanje revolt is considered the first confrontation of the War of Independence in Angola and the Portuguese Colonial War throughout the colonies (then overseas provinces). The uprising began on January 3, 1961 in the region of Baixa do Cassanje, district of Malanje, Portuguese Angola. By January 4, the Portuguese authorities had successfully suppressed the revolt. January 4 is now Colonial Martyrs Repression Day, a national holiday in Angola.
On January 3, agricultural workers employed by Cotonang, a Portuguese-Belgium cotton plantation company, staged a protest to force the company to improve their working conditions. The protest, which later became known as the Baixa de Cassanje revolt, was led by two previously unknown Angolans, António Mariano and Kulu-Xingu. During the protest, the Angolan workers burned their identification cards and physically attacked Portuguese traders on the company premises. The protest led to a general uprising, to which Portuguese authorities responded with an air raid on twenty villages in the area, killing large numbers of Angolan villagers. While the People's Movement for the Liberation of Angola (MPLA) claimed that the air raid killed some ten thousand people, most estimates range from 400 to as many as 7,000 Angolans killed.
On March 15, 1961 the União das Populações de Angola (UPA), led by Holden Roberto, staged a popular revolt in the Bakongo region of northern Angola. Angolan Bantu farmers and coffee-plantation workers joined the uprising and in a frenzy of rage against European settlers and landowners, killed some 1,000 white Angolans in the first days of fighting, together with an unknown number of natives. The rioting workers burned plantations, bridges, government facilities, and police stations, and destroyed several barges and ferries. Graphic images of raped and mutilated settlers inflamed the rage of the Portuguese public, and the Portuguese Army instituted a harsh counter-insurgency campaign that destroyed dozens of villages and killed some 20,000 people, before the uprising was put down in September 1961.