One of the first major revolts of the nationalist struggle was instigated by Bakongo in March 1961 in the northwest. The Portuguese crushed the peasant attack, organized by the Bakongo group, the Union of Angolan Peoples (União das Populações de Angola – UPA), on their settlements, farms, and administrative outposts. Subsequently, 400,000 Bakongo fled into Zaire. In 1962 the UPA formed the National Front for the Liberation of Angola (Frente Nacional de Libertação de Angola – FNLA), which became one of the three major nationalist groups (the other two being the MPLA and UNITA) involved in the long and bloody war of independence. Most of the FNLA's traditional Bakongo constituency fled into exile in Zaire during the war. Following independence, however, many Bakongo exiles returned to their traditional homesteads in Angola. They had since retained their ethnolinguistic integrity.