Garcia was particularly valiant during the desperate battle in the County of Soyo, when the royal army was backed up against the river.

Before an election to replace his brother could be held, Garcia moved forces from Mbamba to the capital and forcibly became king.

Within a few weeks, Paulo, the Count of Soyo and longtime ally, died and was replaced by his and Garcia's enemy Daniel da Silva.

In 1642, he received an embassy from the Dutch and signed an alliance and agreement, but refused to accept a Calvinist preacher from them due to his Catholic background.

[5] Garcia hoped that the Dutch would assist him in driving the Portuguese out of Angola, as these terms had been laid down as early as 1622 when Pedro II of Kongo had proposed the Kongo-Dutch alliance.

Garcia could not commit more forces to the campaign against Portugal due to increasing hostility with Daniel da Silva.

His son and would-be heir, Afonso, was captured while leading the Kongo forces, and a campaign to free him in 1646 failed.

Salvador Correia de Sá, the Portuguese governor, drafted a treaty demanding from Garcia the Island of Luanda, all lands south of the Bengo River, the rights to all mines in Kongo, payment of an indemnity, and other major concessions.