[3] Fresh from a victory against Nambu a Ngongo, a southern neighbor of Kongo, a 20,000 strong Portuguese army with its Imbangala allies entered Mbamba and was met by the Duke at Mbumbi.

Although the Duke's men fought bravely and scattered a portion of the Portuguese army, he was badly outnumbered having only his own small force and that of the Marquis of Mpemba who managed to join him.

[citation needed] Pedro II immediately declared Angola an enemy of the state and brought the main army down from Kongo to meet the invaders at Mbanda Kasi.

Pedro II set up camp at Mbana Kasi and wrote numerous letters of protest to Rome and the king of Spain (then also the ruler of Portugal).

As a result of these letters and protests by Portuguese merchants in Kongo and Angola, João Correia de Sousa was recalled in disgrace, and some 1,200 slaves were eventually returned from Brazil.