of the conflict Beginning of the conflict On 15 March 1961, the Union of Peoples of Angola (UPA), under the leadership of Holden Roberto, launched an incursion into northern Angola from its base in the Congo-Léopoldville (ex-Belgian Congo), leading 4,000 to 5,000 militants. His forces took farms, government outposts, and trading centers, killing and mutilating officials and civilians, most of them Ovimbundu "contract workers" from the Central Highlands. It was the start of the Angolan War of Independence and of the wider Portuguese Overseas War. UPA militants stormed the Angolan districts of Zaire, Uíge, Cuanza Norte and Luanda, massacring the civilian population during their advance, killing 1,000 whites and 6,000 blacks (women and children included of both white European and black African descent). Besides the killing of people, the UPA militants destroyed the infrastructures they found on their way, including houses, farms, roads and bridges, creating a general chaos and panic. The terrified populations took refuge in the forests or fled to nearby regions and to Congo-Léopoldville. However and contrary to the expectations of the UPA, the majority of the white inhabitants that were able to survive the initial attacks did not flee, except some women and children that were evacuated to Luanda. Instead, they entrenched themselves in several towns and villages of the region – including Carmona, Negage, Sanza Pombo, Santa Cruz, Quimbele and Mucaba – resisting the assaults almost without the support of the few existent military forces. On the same day and on the 16th, the 7th and the 9th Special companies and the 1st Paratrooper Company were dispatched from the Metropole to Angola by air. Other small units of the same type were dispatched in the following days. Small military columns left Luanda and Carmona to try to rescue some of the isolated populations of the areas under the UPA attacks. On 21 March, the Provisional Battalion of Major Rebocho Vaz – which has acted in the Baixa de Cassange revolt – moved to Cuanza Norte to face the UPA advances. Without relevant military reinforcements arriving from the Metropole, on 28 March, the Corps of Volunteers of Angola was created, in order to officially frame the civil volunteers that were already fighting the UPA. In early April, the Massacre of Cólua occurred. The village of Cólua, near Aldeia Viçosa, Uíge had been attacked and its inhabitants massacred by the UPA. A military column from the Provisional