No sooner had he come to the throne than the governor of Angola,
João Correia de Sousa, sent an army into Kongo claiming that he had the right to choose the mwenekongo. Besides that, Sousa accused Pedro of harboring runaway slaves from Angola during his tenure as Duke of Mbamba.
Battle of Mbumbi 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. The Portuguese defeated and killed both nobles. They were later eaten by Portugal's Imbangala troops.
Battle of Mbandi Kasi 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. The army of Kongo crushed the Portuguese and the Imbangala and forced them out of Kongo entirely. In the aftermath of this, anti-Portuguese riots broke out all over the kingdom and threatened its long established merchant community. Portuguese throughout the country were humiliatingly disarmed and even forced to give up their clothes. 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. Pedro, anxious not to alienate the Portuguese merchant community, and aware that they had generally remained loyal during the war, did as much as he could to preserve their lives and property, leading some of his detractors to call him "King of Portuguese". ==Birth of the Dutch Alliance==