Portuguese bishops in the kingdom were often favourable to European interests in a time when relations between Kongo and Angola were tense. They refused to appoint priests, forcing Kongo to rely more and more heavily on the laity. Documents of the time show that lay teachers (called "mestres" in Portuguese-language documents) were paid salaries and appointed by the crown, and at times Kongo kings withheld income and services to the bishops and their supporters (a tactic called "country excommunication"). Controlling revenue was vital for Kongo's kings since even Jesuit missionaries were paid salaries from the royal exchequer.