 As Crown Prince Cảnh had died of smallpox during the war against the Tây Sơn , it was assumed that Cảnh 's son would succeed Gia Long , but in 1816 Nguyễn Phúc <unk> , the son of Gia Long 's second wife , was appointed instead . Gia Long chose him for his strong character and his deeply conservative aversion to Westerners , whereas Cảnh 's lineage had converted to Catholicism and had shunned Confucian traditions such as ancestor worship . Gia Long told his son to treat the Europeans — especially the French — respectfully , but not to grant them any position of preponderance . 
