 Minh Mạng disliked Duyệt because he was one of many high @-@ ranking mandarins who opposed Gia Long 's succession plan . Duyệt and many of his southern associates tended to be favourable to Christianity , and supported the installation of Nguyễn Phúc Cảnh 's descendants . As a result , Duyệt was held in high regard by the Catholic community . Historian Mark McLeod said that " As the head of a region enjoying substantial autonomy , Lê Văn Duyệt had good reason to prefer that the empire be ruled after Gia @-@ long 's death by an immature or malleable monarch . " According to McLeod , as Duyệt was not from a scholar @-@ gentry background and lacked a classical Confucian education , he did not place a great emphasis on tradition and was more concerned with military needs , and that as a result , he would be more interested in maintaining strong relations with Europeans so that he could acquire weapons from them , rather than worrying about the social implications of Westernization . There was also speculation that Gia Long was worried that Cảnh 's 18 @-@ year @-@ old heir was too young and could have been manipulated , and that he would forget his Eastern roots , whereas the more mature Minh Mạng — aged 26 — would not . Gia Long was aware of the fact that Catholic clergy were opposed to the installation of Minh Mạng . 
