He was dismissed by the Head of State Bảo Đại under pressure from the French colonial authorities, who resented his pro-American and nationalist attitude.

He was sent to Hanoi to be educated at the Lycée Albert Sarraut, afterward, he returned to Saigon to work as a high school teacher and a journalist.

In 1917 he worked for the La Tribune Indigène and in 1920, he founded the liberal newspaper L'Écho Annamite, in which he worked with the (Eurasian) Vietnamese nationalist Eugène Dejean de la Bâtie,[3] friend of André Malraux.

During his time as a journalist, Long would write about spiritualism and the Vietnamese religion Caodaism.

He was elected in 1936 as president of the Congrès Universel des Sectes Caodaïques, an attempted unified caodai movement, which eventually failed.