 For a time , Duyệt 's attitude and stature in the south forced Minh Mạng to moderate his policies and allow the preaching of Christian missionaries . However , it also increased the tension between the pair and Minh Mạng was anxious to curtail the autonomy that his father had granted to Duyệt and the southerners . The emperor began to slowly wind back their military powers , in an attempt to wear down Duyệt 's power base by gradually removing the general 's close aides . 
