 Afonso was a determined soldier and extended Kongo's effective control to the south.His letter of 5 October 1514 reveals the connections between Afonso's men, Portuguese mercenaries in Kongo's service and the capture and sale of slaves by his forces, many of which he retained in his own service.In 1526 Afonso wrote two letters concerning the slave trade to the king of Portugal, decrying the rapid destabilization of his kingdom as the Portuguese slave traders intensified their efforts.