Thomas De, Dominic Uy, Augustine Moi, Francis Xavier Mau, Francis Man were Vietnamese catechists who were martyred together in 1839 under the persecution of the Emperor Minh Mang. Thomas De was a tailor who entered the Dominicans as a tertiary. Arrested on the charge of giving aid and shelter to foreign missionaries, he was strangled at the age of twenty-six. Augustine Moi, also a Dominican tertiary, worked as a day laborer. When the persecution of the faith started, he was ordered to trample a crucifix, an act he refused. He too was strangled for his loyalty to Christ. Francis Xavier Mau was a native catechist who was strangled to death with the other four martyrs. Francis Man was a Dominican tertiary, who was serving as a catechist when he was arrested.
At this time we also remember St Peter Truat and St Peter Duong, who were catechists martyred on 18 December 1838, and St Peter Thi, who worked in the missions with the priests of the Foreign Mission Society of Paris. Imprisoned and repeatedly tortured, he was beheaded in Ô Cau Giay, Hanoi, Vietnam on 20 December 1839.