In 1641, the Dutch invaded Angola and captured Luanda, after an almost bloodless struggle. They immediately sought to renew their alliance with Kongo, which had had a false start in 1624, when Garcia I refused to assist a Dutch attack on Luanda. While relations between Sao Salvador and Luanda were not warm, the two polities had enjoyed an easy peace, due to the former's internal distractions, and the latter's war against the Kingdom of Matamba. The same year of the Portuguese ouster from Luanda, Kongo entered into a formal agreement with the new government, and agreed to provide military assistance as needed. Garcia II ejected nearly all Portuguese and Luso-African merchants from his kingdom. The colony of Angola was declared an enemy once again, and the Duke of Mbamba was sent with an army to assist the Dutch. The Dutch also provided Kongo with military assistance, in exchange for payment in slaves.