Paper short abstract:

The Kingdom of Kongo participated in the overseas portions of the 30 Years war as an ally of the Netherlands which resulted in the Dutch occupation of Luanda in 1641.

Paper long abstract:

King Pedro II of Kongo initiated an alliance with the Dutch States General and West India Company in 1622 when he repelled a Portuguese attack on Kongo. Seeking revenge and security from further Portuguese threats, he proposed a joint attack on Luanda with Dutch and Kongo forces operating in alliance. The Dutch accepted this invitation, and sought to attack Luanda in 1624, though Pedro's successor Garcia I ultimately declined to assist them. The alliance remained in effect however, and was renewed in 1641 when the Dutch attacked Luanda again. This time Garcia II, a later king, joined the Dutch enthusiastically, assuring the Dutch occupation of Luanda.