Phan Bội Châu
Details about Cẩn's early life are scarce. In his youth, he had studied the writings and opinions of the renowned anti-French Vietnamese nationalist Phan Bội Châu, who spent his last years in Huế. Regarded as the leading revolutionary of his time, Châu had been captured and sentenced to death, before having his sentence reduced to house arrest. Cẩn regularly traveled to Châu's sampan on the Perfume River with gifts of food and listened to Châu's political lectures. Regarded as the least educated of his family, Cẩn had never traveled outside Vietnam and was the only Ngô brother not to have studied at a European-run institution.