Diogo I Nkumbi a Mpudi was manikongo in 1545-1561. King Diogo was the grandson of king Afonso I of Kongo and won the throne after overthrowing his uncle Pedro Nkanga a Mvemba and forcing him to take refuge in a church in São Salvador. Diogo's early struggles are documented in a legal inquest he conducted in 1550 into a plot against him launched by the former king. In 1555, the king cut all ties with the Portuguese whom he saw as meddlesome and a threat to the kingdom and expelled all 70 Portuguese inhabitants from the kingdom.
King Diogo was anxious to extend the Roman Catholic faith in Kongo, work already started by Afonso I during his reign and due to Portuguese influence. Though Afonso had created a model for the Roman Catholic Church in Kongo, Diogo hoped to extend it throughout the rural areas and also into neighboring countries. After his death in 1561, he was succeeded by illegitimate son Afonso II.